AUT. lil. PARASITES OF SHAEKS AND SKATES — LINTON. 7 



C obscurvs. 



Collected in nine of the years from 1905 to 1918 : On four dates in 

 July, few to many, maximum length 26 mm. (one date, few in 1 of 

 3 sharks), 6 sharks examined; on eight dates in August, 1 to numer- 

 ous in each of 11 sharks; on three dates in September, 2 to 12, and 

 numerous free proglottides in 3 sharks. 



It is to be remarked that the size of the host is no index of the 

 number of parasites. For example. 3 of this cestode were found 

 in a shark measuring 305 centimeters in length, many in a 110 centi- 

 meter shark, and 1 in a 165 centimeter shark. 



It is likely that many of the sharks of the Woods Hole region, 

 recorded as C. ohseurns, were either C. milherti or G. commersonii. 

 With the identification of species based on the character of the 

 denticles, C. milherti was found to be abundant. C. commersonii was 

 noted, C. ohscurus was not seen. For many of the identifications of 

 sharks in the summer of 1922 I am indebted to Dr. H. M. Smith. In 

 the summer of 1923 the 17 sharks belonging to the genus Carchar- 

 hinvs that were examined were all found to be C. commersonii. 



Cestracion sygaena. 



1908, August 3: Several small strobiles and fragments scolecea 

 macerated, one of them evidently ^4. lociniatwn. 



Galeus glaucus. 



1905, August 5: 12, rather, small scoleces of most of them im- 

 perfect, apparently macerated ; two were filiform at the anterior end. 



1913, July 5 : Several fragments, but no scoleces. 



1923, July 23:46, from a 245-centimeter shark; all small, maxi- 

 mum length 10 mm. 



Ra'ja eglanteria. 



1905, August 12 : 2 scoleces. Referred with some hesitation to this 

 species. A memorandum sketch of the ova shows them to be circular 

 in outline, with a thin shell which is separated from a segmenting 

 cell mass by a clear space; diameter of shell 0.03^ of cell mass 0.02. 

 A memorandum sketch of an everted cirrus shows it to be slightly 

 constricted near the base, then swollen and tapering gradually to the 

 tip, and armed with short spines (fig. Ic). 



Scoliodon terrae-novae. 

 1915, July 15 : Few. 



201S3— 25— Pi-<)('.N.M.vol.G4 34 



