36 PKOOEEDINGS OF THE NATIONAL MUSEUM. vol.64. 



middle and outer prongs about equal, inner prong much reduced, 

 inner end of transverse bar blunt. 



Strobile. — General characters as in P. lasium but rather stouter; 

 spines on neck rather more slender; adult proglottides somewhat 

 rounded, so that the posterior end of the strobile may become monili- 

 form; anatomy of proglottis, so far as observed, differs little from 

 that of P. lasium; free, ripe proglottides not yet certainly identified. 



Measurements of four specimens mounted in balsam gave the fol- 

 lowing results : 



Length of strobile 20.00 27.00 23.00 22.00 



Breadth of scolex, excluding hooks 0. 70 0. 70 0. 56 0. 63 



Length of scolex 0. 70 0. 70 0. 56 0. 63 



Length of longest hook 0. 18 0. 14 0. 15 0. 165 



Length of spines on neck, maximum 0. 015 0. 015 0. 012 0. 012 



Distance to first distinct segment 2. 50 3. 00 1. 68 1. 48 



Length of posterior segments 1. 05 1. 96 1. 12 0. 98 



Breadth of posterior segments 0. 63 0. 43 0. 56 0. 42 



This species has been recorded from G archnrhinus obscurus, at 

 Woods Hole, Mass., and Beaufort, N. C, and from Scoliodon terrae- 

 novae^ at Beaufort. 



The following additional finds of this species were all made at 

 Woods Hole. 



Garcharhinus milberti. 



1922, July 3: 4, with 69 A. laciniatum., 6, C. angustum, and 185 

 P. lasium. August 15 : 5, maximum length, 30 mm. 



(U.S.N.M., Hehn. Coll. 7686.) 



Garcharhinus obscurus. 



1905, July 28 : Few, longest, 25 mm. August 11:1. 

 1910, July 25 : 10. 

 1914, July 11 : 3. 



PHOREIOBOTHRIUM PECTINATUM, new species. 



Plate 5, figs. 47-50. 



Phoreiobothrium lasium, 1900, p. 273 ; 1901, p. 428. 



Scolex. — Smaller and relatively shorter that in either of the fore- 

 going species; about seven loculi at posterior end of bothrium; the 

 costa in front of the loculi is bordered with about seventeen short, 

 flat, rounded, and scale-like papillae. The hooks are much like 

 those of P. lasimn^ but smaller; moreover, the hooks of a pair are 

 not symmetrical, the inner prong of one hook being much shorter 

 than the other two, while the inner prong of the other hook is of 

 nearly the same length as the two others (fig. 48). The horizontal 

 bar of the hooks is relatively broader than in P. lasium, and the 

 inner end projects very little. 



