The Securities and Exchange Commission has not necessarily reviewed the information in this filing and has not determined if it is accurate and complete.
The reader should not assume that the information is accurate and complete.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM 13F

FORM 13F INFORMATION TABLE
OMB APPROVAL
OMB Number: 3235-0006
Estimated average burden
hours per response: 23.8
COLUMN 1 COLUMN 2 COLUMN 3 COLUMN 4 COLUMN 5 COLUMN 6 COLUMN 7 COLUMN 8
VALUE SHRS OR SH/ PUT/ INVESTMENT OTHER VOTING AUTHORITY
NAME OF ISSUER TITLE OF CLASS CUSIP (x$1000) PRN AMT PRN CALL DISCRETION MANAGER SOLE SHARED NONE
3M CO COM COM 88579Y101 1,337 6,345 SH   SOLE   6,345 0 0
ABBOTT LABS COM COM 002824100 727 9,908 SH   SOLE   9,908 0 0
ACCENTURE PLC IRELAND SHS CLAS SHS CLASS A G1151C101 873 5,130 SH   SOLE   5,130 0 0
AFLAC INC COM COM 001055102 240 5,107 SH   SOLE   5,107 0 0
ALPHABET INC CAP STK CL A CAP STK CL A 02079K305 2,817 2,334 SH   SOLE   2,334 0 0
ALPHABET INC CAP STK CL C CAP STK CL C 02079K107 769 644 SH   SOLE   644 0 0
ALTRIA GROUP INC COM COM 02209S103 255 4,227 SH   SOLE   4,227 0 0
AMAZON COM INC COM COM 023135106 2,598 1,297 SH   SOLE   1,297 0 0
AMERICAN EXPRESS CO COM COM 025816109 1,108 10,401 SH   SOLE   10,401 0 0
AMETEK INC NEW COM COM 031100100 27,319 345,290 SH   SOLE   345,290 0 0
AMGEN INC COM COM 031162100 237 1,143 SH   SOLE   1,143 0 0
AMPHENOL CORP NEW CL A CL A 032095101 7,638 81,242 SH   SOLE   81,242 0 0
ANGIODYNAMICS INC COM COM 03475V101 355 16,325 SH   SOLE   16,325 0 0
ANHEUSER BUSCH INBEV SA/NV SPO SPONSORED ADR 03524A108 13,189 150,613 SH   SOLE   150,613 0 0
APPLE INC COM COM 037833100 8,826 39,096 SH   SOLE   39,096 0 0
ARCH CAP GROUP LTD ORD ORD G0450A105 20,295 680,815 SH   SOLE   680,815 0 0
BADGER METER INC COM COM 056525108 212 4,000 SH   SOLE   4,000 0 0
BANK AMER CORP COM COM 060505104 1,608 54,580 SH   SOLE   54,580 0 0
BANK NEW YORK MELLON CORP COM COM 064058100 431 8,444 SH   SOLE   8,444 0 0
BECTON DICKINSON & CO COM COM 075887109 345 1,322 SH   SOLE   1,322 0 0
BERKSHIRE HATHAWAY CLASS B CL B NEW 084670702 14,005 65,409 SH   SOLE   65,409 0 0
BLACKROCK INC COM COM 09247X101 1,314 2,787 SH   SOLE   2,787 0 0
BOEING CO COM COM 097023105 268 721 SH   SOLE   721 0 0
BOOKING HLDGS INC COM COM 09857L108 9,436 4,756 SH   SOLE   4,756 0 0
BROWN FORMAN CORP CL B CL B 115637209 336 6,641 SH   SOLE   6,641 0 0
CAE INC COM COM 124765108 1,165 57,345 SH   SOLE   57,345 0 0
CAMBRIDGE BANCORP COM COM 132152109 735 8,171 SH   SOLE   8,171 0 0
CANADIAN PAC RY LTD COM COM 13645T100 20,660 97,480 SH   SOLE   97,480 0 0
CASS INFORMATION SYS INC COM COM 14808P109 1,023 15,713 SH   SOLE   15,713 0 0
CHARTER COMMUNICATIONS INC NEW CL A 16119P108 226 695 SH   SOLE   695 0 0
CHUBB LIMITED COM COM H1467J104 477 3,570 SH   SOLE   3,570 0 0
CITIGROUP INC COM NEW COM NEW 172967424 207 2,892 SH   SOLE   2,892 0 0
CLEARWAY ENERGY INC CL C CL C 18539C204 597 31,000 SH   SOLE   31,000 0 0
COLGATE PALMOLIVE CO COM COM 194162103 6,229 93,045 SH   SOLE   93,045 0 0
COMCAST CORP NEW CL A CL A 20030N101 1,369 38,671 SH   SOLE   38,671 0 0
CONOCOPHILLIPS COM COM 20825C104 646 8,347 SH   SOLE   8,347 0 0
COPART INC COM COM 217204106 8,710 169,029 SH   SOLE   169,029 0 0
CSW INDUSTRIALS INC COM COM 126402106 419 7,800 SH   SOLE   7,800 0 0
DIAGEO P L C SPON ADR NEW SPON ADR NEW 25243Q205 812 5,732 SH   SOLE   5,732 0 0
DIAMOND HILL INVESTMENT GROUP COM NEW 25264R207 837 5,063 SH   SOLE   5,063 0 0
DORMAN PRODUCTS INC COM COM 258278100 15,807 205,495 SH   SOLE   205,495 0 0
DOWDUPONT INC COM COM 26078J100 970 15,081 SH   SOLE   15,081 0 0
DUKE ENERGY CORP NEW COM NEW COM NEW 26441C204 250 3,128 SH   SOLE   3,128 0 0
EATON CORP PLC SHS SHS G29183103 427 4,929 SH   SOLE   4,929 0 0
ENSTAR GROUP LIMITED SHS SHS G3075P101 995 4,770 SH   SOLE   4,770 0 0
ENTEGRIS INC COM COM 29362U104 1,757 60,680 SH   SOLE   60,680 0 0
EQUITY COMWLTH COM SH BEN INT COM SH BEN INT 294628102 5,206 162,240 SH   SOLE   162,240 0 0
EXXON MOBIL CORP COM COM 30231G102 440 5,170 SH   SOLE   5,170 0 0
FACEBOOK INC CL A CL A 30303M102 383 2,326 SH   SOLE   2,326 0 0
FEDEX CORP COM COM 31428X106 436 1,811 SH   SOLE   1,811 0 0
FRP HLDGS INC COM COM 30292L107 280 4,515 SH   SOLE   4,515 0 0
GRACO INC COM COM 384109104 8,317 179,475 SH   SOLE   179,475 0 0
HEICO CORP NEW CL A CL A 422806208 48,454 641,770 SH   SOLE   641,770 0 0
HEXCEL CORP NEW COM COM 428291108 22,470 335,130 SH   SOLE   335,130 0 0
HINGHAM INSTN SVGS MASS COM COM 433323102 12,399 56,409 SH   SOLE   56,409 0 0
HOME DEPOT INC COM COM 437076102 400 1,932 SH   SOLE   1,932 0 0
HONEYWELL INTL INC COM COM 438516106 287 1,722 SH   SOLE   1,722 0 0
HOWARD HUGHES CORP COM COM 44267D107 1,205 9,700 SH   SOLE   9,700 0 0
IDEX CORP COM COM 45167R104 13,438 89,196 SH   SOLE   89,196 0 0
ILLINOIS TOOL WKS INC COM COM 452308109 969 6,870 SH   SOLE   6,870 0 0
INGREDION INC COM COM 457187102 15,968 152,135 SH   SOLE   152,135 0 0
INTEL CORP COM COM 458140100 2,658 56,206 SH   SOLE   56,206 0 0
INTERCONTINENTAL EXCHANGE INC COM 45866F104 19,239 256,894 SH   SOLE   256,894 0 0
INTERNATIONAL BUSINESS MACHS C COM 459200101 763 5,043 SH   SOLE   5,043 0 0
ISHARES GOLD TRUST ISHARES ISHARES 464285105 488 42,700 SH   SOLE   42,700 0 0
JOHNSON & JOHNSON COM COM 478160104 2,882 20,855 SH   SOLE   20,855 0 0
JPMORGAN CHASE & CO COM COM 46625H100 7,288 64,589 SH   SOLE   64,589 0 0
KAR AUCTION SVCS INC COM COM 48238T109 20,434 342,340 SH   SOLE   342,340 0 0
LCI INDS COM COM 50189K103 3,470 41,910 SH   SOLE   41,910 0 0
LEGACY TEX FINL GROUP INC COM COM 52471Y106 19,194 450,573 SH   SOLE   450,573 0 0
M & T BK CORP COM COM 55261F104 15,343 93,247 SH   SOLE   93,247 0 0
MARTIN MARIETTA MATLS INC COM COM 573284106 300 1,649 SH   SOLE   1,649 0 0
MASTERCARD INCORPORATED CL A CL A 57636Q104 14,176 63,679 SH   SOLE   63,679 0 0
MCDONALDS CORP COM COM 580135101 261 1,561 SH   SOLE   1,561 0 0
MEDTRONIC PLC SHS SHS G5960L103 287 2,920 SH   SOLE   2,920 0 0
MERCK & CO INC COM COM 58933Y105 1,028 14,492 SH   SOLE   14,492 0 0
MICROSOFT CORP COM COM 594918104 6,271 54,832 SH   SOLE   54,832 0 0
MOHAWK INDS INC COM COM 608190104 3,998 22,800 SH   SOLE   22,800 0 0
MONDELEZ INTL INC CL A CL A 609207105 402 9,346 SH   SOLE   9,346 0 0
NEWMARKET CORP COM COM 651587107 8,108 19,995 SH   SOLE   19,995 0 0
NIKE INC CL B CL B 654106103 377 4,450 SH   SOLE   4,450 0 0
NORTHERN TR CORP COM COM 665859104 566 5,546 SH   SOLE   5,546 0 0
NOVARTIS A G SPONSORED ADR SPONSORED ADR 66987V109 721 8,367 SH   SOLE   8,367 0 0
NVE CORP COM NEW COM NEW 629445206 289 2,726 SH   SOLE   2,726 0 0
O REILLY AUTOMOTIVE INC NEW CO COM 67103H107 14,141 40,714 SH   SOLE   40,714 0 0
ORACLE CORP COM COM 68389X105 291 5,644 SH   SOLE   5,644 0 0
PAYPAL HLDGS INC COM COM 70450Y103 2,469 28,112 SH   SOLE   28,112 0 0
PEPSICO INC COM COM 713448108 756 6,765 SH   SOLE   6,765 0 0
PERMIAN BASIN RTY TR UNIT BEN UNIT BEN INT 714236106 99 12,500 SH   SOLE   12,500 0 0
PETROLEO BRASILEIRO SA PETROBR SP ADR NON VTG 71654V101 959 91,657 SH   SOLE   91,657 0 0
PETROLEO BRASILEIRO SA PETROBR SPONSORED ADR 71654V408 341 28,233 SH   SOLE   28,233 0 0
PFIZER INC COM COM 717081103 681 15,444 SH   SOLE   15,444 0 0
PHILIP MORRIS INTL INC COM COM 718172109 223 2,736 SH   SOLE   2,736 0 0
PHILLIPS 66 COM COM 718546104 265 2,352 SH   SOLE   2,352 0 0
PRAXAIR INC COM COM 74005P104 20,057 124,787 SH   SOLE   124,787 0 0
RBC BEARINGS INC COM COM 75524B104 20,950 139,329 SH   SOLE   139,329 0 0
RLI CORP COM COM 749607107 25,809 328,444 SH   SOLE   328,444 0 0
ROPER TECHNOLOGIES INC COM COM 776696106 14,345 48,428 SH   SOLE   48,428 0 0
ROYAL DUTCH SHELL PLC SPONS AD SPONS ADR A 780259206 556 8,163 SH   SOLE   8,163 0 0
SCHEIN HENRY INC COM COM 806407102 14,195 166,939 SH   SOLE   166,939 0 0
SEMGROUP CORP CL A CL A 81663A105 7,813 354,316 SH   SOLE   354,316 0 0
STARBUCKS CORP COM COM 855244109 1,296 22,796 SH   SOLE   22,796 0 0
TARGA RES CORP COM COM 87612G101 9,315 165,419 SH   SOLE   165,419 0 0
TD AMERITRADE HLDG CORP COM COM 87236Y108 808 15,291 SH   SOLE   15,291 0 0
TE CONNECTIVITY LTD REG SHS REG SHS H84989104 16,487 187,505 SH   SOLE   187,505 0 0
TELEDYNE TECHNOLOGIES INC COM COM 879360105 20,011 81,120 SH   SOLE   81,120 0 0
TEXAS INSTRS INC COM COM 882508104 2,744 25,579 SH   SOLE   25,579 0 0
TEXAS PAC LD TR SUB CTF PROP I SUB CTF PROP I T 882610108 673 780 SH   SOLE   780 0 0
TRAVELERS COMPANIES INC COM COM 89417E109 214 1,646 SH   SOLE   1,646 0 0
TWITTER INC COM COM 90184L102 309 10,848 SH   SOLE   10,848 0 0
UNILEVER N V N Y SHS NEW N Y SHS NEW 904784709 472 8,500 SH   SOLE   8,500 0 0
UNILEVER PLC SPON ADR NEW SPON ADR NEW 904767704 575 10,462 SH   SOLE   10,462 0 0
UNITED TECHNOLOGIES CORP COM COM 913017109 923 6,604 SH   SOLE   6,604 0 0
UNITEDHEALTH GROUP INC COM COM 91324P102 2,410 9,059 SH   SOLE   9,059 0 0
US BANCORP DEL COM NEW COM NEW 902973304 354 6,698 SH   SOLE   6,698 0 0
UTAH MED PRODS INC COM COM 917488108 523 5,555 SH   SOLE   5,555 0 0
VANGUARD SCOTTSDALE FDS SHRT T SHRT TRM CORP BD 92206C409 216 2,762 SH   SOLE   2,762 0 0
VERSUM MATLS INC COM COM 92532W103 10,028 278,475 SH   SOLE   278,475 0 0
VISA INC COM CL A COM CL A 92826C839 11,484 76,515 SH   SOLE   76,515 0 0
WATERS CORP COM COM 941848103 303 1,557 SH   SOLE   1,557 0 0
WELLS FARGO CO NEW COM COM 949746101 1,209 22,993 SH   SOLE   22,993 0 0
WHITE MTNS INS GROUP LTD COM COM G9618E107 8,470 9,050 SH   SOLE   9,050 0 0
WILLIAMS COS INC DEL COM COM 969457100 8,202 301,643 SH   SOLE   301,643 0 0
WINMARK CORP COM COM 974250102 3,981 23,980 SH   SOLE   23,980 0 0
ANTERO MIDSTREAM PARTNERS LP U UNT LTD PARTN 03673L103 7,998 279,043 SH   SOLE   279,043 0 0
BROOKFIELD INFRAST PARTNERS LP LP INT UNIT G16252101 215 5,400 SH   SOLE   5,400 0 0
BROOKFIELD RENEWABLE PARTNERS PARTNERSHIP UNIT G16258108 206 6,800 SH   SOLE   6,800 0 0
ENERGY TRANSFER EQUITY L P COM COM UT LTD PTN 29273V100 9,045 518,945 SH   SOLE   518,945 0 0
ENLINK MIDSTREAM LLC COM UNIT COM UNIT REP LTD 29336T100 7,851 477,269 SH   SOLE   477,269 0 0
ENTERPRISE PRODS PARTNERS L P COM 293792107 8,092 281,640 SH   SOLE   281,640 0 0
EQT GP HLDGS LP COM UNIT REP COM UNIT REP 26885J103 3,644 174,922 SH   SOLE   174,922 0 0
EQT MIDSTREAM PARTNERS LP UNIT UNIT LTD PARTN 26885B100 4,531 85,844 SH   SOLE   85,844 0 0
HANNON ARMSTRONG SUST INFR CAP COM 41068X100 644 30,000 SH   SOLE   30,000 0 0
MPLX LP COM UNIT REP LTD COM UNIT REP LTD 55336V100 8,039 231,793 SH   SOLE   231,793 0 0
NOBLE MIDSTREAM PARTNERS LP CO COM UNIT REPST 65506L105 5,371 151,681 SH   SOLE   151,681 0 0
ONEOK INC NEW COM COM 682680103 8,395 123,850 SH   SOLE   123,850 0 0
PHILLIPS 66 PARTNERS LP COM UN COM UNIT REP INT 718549207 8,259 161,487 SH   SOLE   161,487 0 0
SHELL MIDSTREAM PARTNERS L P U UNIT LTD INT 822634101 8,100 378,875 SH   SOLE   378,875 0 0
VALERO ENERGY PARTNERS LP COM COM UNT REP LP 91914J102 7,627 201,338 SH   SOLE   201,338 0 0
WESTERN GAS EQUITY PARTNERS LP COMUNT LTD PT 95825R103 6,914 230,945 SH   SOLE   230,945 0 0
WESTERN GAS PARTNERS LP COM UN COM UNIT LP IN 958254104 441 10,100 SH   SOLE   10,100 0 0
DBX ETF TR XTRACK MSCI EURP XTRACK MSCI EURP 233051853 269 9,405 SH   SOLE   9,405 0 0
INVESCO EXCHANGE TRADED FD TR S&P500 EQL WGT 46137V357 18,362 171,914 SH   SOLE   171,914 0 0
ISHARES INC MSCI PAC JP ETF MSCI PAC JP ETF 464286665 229 5,045 SH   SOLE   5,045 0 0
ISHARES TR CORE S&P MCP ETF CORE S&P MCP ETF 464287507 221 1,098 SH   SOLE   1,098 0 0
ISHARES TR CORE S&P SCP ETF CORE S&P SCP ETF 464287804 1,944 22,285 SH   SOLE   22,285 0 0
ISHARES TR MSCI ACWI ETF MSCI ACWI ETF 464288257 223 3,000 SH   SOLE   3,000 0 0
ISHARES TR MSCI UK SM ETF MSCI UK SM ETF 46429B416 284 6,800 SH   SOLE   6,800 0 0
ISHARES TR RUS 1000 VAL ETF RUS 1000 VAL ETF 464287598 276 2,176 SH   SOLE   2,176 0 0
ISHARES TR RUS MDCP VAL ETF RUS MDCP VAL ETF 464287473 9,520 105,468 SH   SOLE   105,468 0 0
ISHARES TR SELECT DIVID ETF SELECT DIVID ETF 464287168 17,498 175,401 SH   SOLE   175,401 0 0
SCHWAB STRATEGIC TR INTL EQTY INTL EQTY ETF 808524805 1,841 54,900 SH   SOLE   54,900 0 0
SPDR S&P 500 ETF TR TR UNIT TR UNIT 78462F103 11,646 40,060 SH   SOLE   40,060 0 0
VANGUARD INDEX FDS TOTAL STK M TOTAL STK MKT 922908769 522 3,485 SH   SOLE   3,485 0 0
VANGUARD TAX MANAGED INTL FD F FTSE DEV MKT ETF 921943858 621 14,345 SH   SOLE   14,345 0 0
VANGUARD WHITEHALL FDS INC HIG HIGH DIV YLD 921946406 1,177 13,515 SH   SOLE   13,515 0 0