[37] NOTES ON ENTOZOA OF MARINE FISHES. 755 



other cases, aud usually in those with evident neck, the laciuise, instead 

 of being long aud slender, are short, stout, and truncate at the distal 

 end. Median segments short and crowded, somewhat flattened, and 

 with bluntly rounded lacinise, or with a broad crenulation on posterior 

 edge. The following segments increase in length, becoming at first as 

 long as broad, subsequently longer than broad. The posterior seg- 

 ments, which may be three times as long as broad, frequently have the 

 anterior end constricted into a short button-like process. The lacinire 

 persist, but are shorter, broader, aud more rounded than at first. Some- 

 times the posterior edges of the segments are reflexed. 



Genital apertures marginal, approximate, about the anterior third or 

 fourth. Length, 25 mm . 



Habitat. — Garcharias obscurus, spiral vaive, Wood's Holl, Massachu- 

 setts, August, 1884; July 25, 1887, and August 12, 1887. 



This species is near Anthobothrium cornucopia Van Beneden, from 

 Galeus canis, but differs from it in its smaller size and relatively short 

 neck. The length of A. cornucopia is given as 250 mm , while the maxi- 

 mum length of A. laciniatum, so far as I have observed, is 25 nuu . Al- 

 though no specimens were found whose proglottides contained ova, 

 many were found in which the posterior segments were in other respects 

 mature, and separated naturally from the strobile. 



Amidst the great variety of forms represented by this species there 

 are two which differ so much from each other that it may become nec- 

 essary to classify them as constant varieties, in which event they may 

 be named from their principal differential characteristics, var. brevicolle 

 and var. filicolle. 



The former is characterized by having a short or even no proper 

 neck, and usually slender, sharp-pointed laciuire on the first segments. 

 The latter has an evident neck, and often short, broad, truncate lacinioe 

 on the first segments. For the present, however, I prefer to regard 

 these apparent varieties as simply different conditions of contraction, 

 on account of which the short neck of some becomes more or less elon- 

 gated in others. 



In my explanations of figures I have, for convenience, made use of 

 the terms var. brevicolle and var. filicolle. These and other character- 

 istic forms are further described in the following detailed account of 

 the species. 



I have obtained this parasite on three different occasions, each time 

 from the same host, namely, the dusky shark {Garcharias obscurus). 



