THE SCOLEX POLYMORFHUS 827 
The close resemblance of our 8. polymorphus to the forms upon 
which Monticelli (op. cit.) worked, makes a discussion of the anat- 
omy superfluous beyond what is shown by my figures and their 
explanations which have been made quite full. The differences 
are only of a minor nature and hence this author’s account is 
adequate for the anatomy of our forms. 
THE NORMAL OCCURRENCE OF PARASITES IN SAND SHARKS 
TAKEN AT RANDOM 
A knowledge of the normal content of parasites found in the 
sharks, as collected, was important both for its bearing upon the 
results of treatment which attempted to rid them of all parasites, 
and upon the results of any artificial infection with young cestodes. 
There are very few sand sharks examined which have not some 
infection with Crossobothrium laciniatum, which is the only ces- 
tode parasite known to infect the digestive tract of this hostin 
considerable numbers. Some records by Linton (’99, p. 429) 
are here tabulated as quite representative of any dozen specimens 
taken at random. 
Table from Linton’s records 
bare | oe gers | oar 
alge 7) GOO aber RE et ges. | 1 20 
Dilys 2 Sst SOOM ey Aaa ee eee ry ties cn Pee | 1 several 
PANT OUIS GN HO el OOO Mepawerts ani rama taicas aeeier | 1 numerous 
ANSI S G2 SO OMe «ate lta hie o 5 aegers lel: i 2 
TSE LSS SOO) ean ere tami Meech wh: 4 op hs 1 i! 
ANI SUS tdi SS Oprrr cae ann eck. Che shag sho th: i 4 
Aupast WS 1S Oot seem erica! aise sie ats a al 55 
ANI CUISTOLO MS 90 ee pe ee eer cent e e 1 12 
SFU ys UD OO Scare ee te eee ey aha | 1 47 
uly 20; LODO os. Seppe eter ae, nee 1 16 
August, L261 G00 Re er es en iin let etree | il numerous 
August 15 LOO cs oct m Ane SARS, | 1 106 
From my own records, the results are similar, though the counts 
are usually higher because a careful search was being made for 
the small young specimens. The following table is from six 
sharks examined in 1904. 
