AUT. 21. PARASITES OF SHARKS AND SKATES LINTON. 39 



to first segments, 25 ; length of fii-st distinct segments, 0.08 ; breadth, 

 0.28; length of posterior segments, 1.05, breadth 0.54; length of 

 spines on neck, 0.012. 



On August 20, 1914, two of these cestodes were found in the Sharp- 

 nosed Shark {Scoliodon terrae-novae) . They measured 45 and 50 

 millimeters, respectively, lying in sea water. Tlie neck was armed 

 with short, triangular spines, about 0.015 mm. in length; strobiles 

 spinose, sparsely so on posterior proglottides, which were immature. 

 Length of hooks, 0.14; breadth of pair of hooks 0.25; breadth of 

 scolex, 0.50 ; length of posterior proglottides, 0.70, breadth, 0.53. 



On August 12, 1915, a few of these cestodes were found in each of 

 two blue sharks {C archarhinus milberti). Two of them in balsam 

 measure 24 and 36 mm, respectively. The necks are densely, and the 

 strobiles sparsely, spinose. 



C cammersomi. 



1923, August 4 : 1, length 36 mm., in alcohol. 30 : 1. 

 GoUeus glauGus. 



1923, July 23 : 77, young strobiles, maximum length about 16 mm. ; 

 densely spinose, length of spines about 0.02 mm. 



(U.S.N.M., Helm. Coll. 7689). 



This cestode has many features in common with Phoriohotht'iuTn. 

 The neck is elongated, and both neck and proglottides are spinose, a 

 feature that was not noted in the original description. There is an 

 elliptical auxiliary sucker at the anterior end of each bothrium in 

 front of the hooks. The posterior proglottides were sufficiently de- 

 veloped to show the following characters : The genital pores are at 

 about the middle point of the lateral margin and are irregularly al- 

 ternate. The vagina lies m front of the cirrus-pouCh, passes antero- 

 mediad to the median line, thence, posteriorly, to the ovary at the 

 posterior end of the proglottis. The vitellaria are best seen along the 

 lateral margins but can be seen to form a continuous layer within the 

 body wall. The cirrus-pouch was still rudimentary ; its course from 

 the margin is at first postero-mediad, then antero-mediad, with indi- 

 cations that coils of the vas deferens are enclosed in the median por- 

 tion. The most conspicuous organs are the testes which fill the pro- 

 glottis from the ovary to near the anterior end which for a short 

 space is free from genitalia. 



PLATYBOTHRIUM PARVUM Linton. 



Plate 5, figs. 52 and 53. 



1900, PlatybotJirium, species, pp. 278, 300. pi. 42, figs. 98, 99. 



1901, pp. 426, 428, 430. 

 1911, p. 587. 



Since the above records were made this species has been found at 

 Woods Hole on the following occasions. 

 20183— 25— rroc.N.M.vol.r)4 30 



