ifl 



[57] NOTES ON ENTOZOA OF MARINE FISHES. 773 



in places contains a fine granular substance. The latter vessel I take 

 to represent the irregular longitudinal marginal vessel noticed in the 

 living specimens, and which may be a nervous vessel. 



In sections of the head the bottoms of the faces of a marginal pair of 

 bothria lie very close together. The inner core of the head is thus very 

 narrow, and composed mainly of coarse longitudinal fibers, with an inner 

 granular core in which lie the aquiferous vessels. This species appears 

 to be near Echeneibothrium tumidulum Eudolphi.* 



The published descriptions of E. tumidulum, however, agree, in the 

 main, in saying that the first segments are extremely long and narrow, 

 and that the bothria are divided into loculi by transverse costoe and a 

 median partition. 



The former of these differences might be reconciled by supposing that 

 the pseudo-segments of R. cancellatum have been taken for true seg- 

 ments by former describers. 



The difference between the bothria of -R. cancellatum and E. tumidulum 

 is too profound to admit of reconciliation. No median row of loculi is 

 shown in any of the published figures of E. tumidulum that I have seen, 

 while in R. cancellatum it is very evident and could not possibly be mis- 

 taken for a median partition. 



12. Rhinebothrium longicolle sp. nov. 

 [Plate VI, Figs. 1-4.] 



Bothria four, marginal, linear-oblong, attached at middle point by 

 short pedicels, ends free, margins crenulate, faces boat-shaped, deeply 

 concave from side to side or with edges appressed, divided into loculi 

 by about twenty-four transverse costte and a median partition, very 

 versatile. Neck long, slender, smooth, cylindrical, rounded posteriorly 

 and separated from the body by a constriction. Body behind constric- 

 tion a little smaller than base of neck, at first cylindrical and crossed by 

 minute transverse lines which soon give rise to distinct segments. Seg- 

 ments at first very short, increasing in length uniformly, near poste- 

 rior end as long as broad with posterior edge very slightly overlapping 

 succeeding segment. Posterior segmeut elongated or, if contracted, 

 with very convex margins. 



Genital apertures marginal, male and female approximate. Length, 

 28 mm ; breadth, .6 mm . 



Habitat. Myliobatisfreminvillei, spiral valve; two specimens. Wood's 

 Holl, Massachusetts, August 5, 1887. 



This description is based on two specimens from the spiral valve of 

 the sharp-nosed ray (Myliobatis freminvillei}: The stomach of the host 

 was empty and there were no other parasites found. 



* Botliriocephaliis tumiduliis Rnd., B. Echeneis Lenckart, Petalocephalus tuiniduliis 



9 



Van Lith de Jeude, Tetraboihrium tumidithtm Rud. Dies, and Echeneibothrium tinnidu- 

 lum Beueden, Dies. 



