544 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
is made of entozoa from this host either in the compilations of Diesing 
and Yon Linstow or in the memoirs of Yan Benedeu, Molin, Oerley, 
Zschokke, etc., who have investigated the entozoa of the Selachians. 
In the first two finds this parasite was the sole occupant of the spiral 
valve. In the last there were associated with it in the same 
several small cestods apparently identical with Orygmatobothrium ng > 
turn Lt. There were also a few scolices of a Tetrarhynchus attached t.o 
the walls of the stomach. A few large neinatods were found in the 
stomach of each host. In the first and third finds there were a few long, 
slender, free proglottides not belonging to this species. These have not 
yet been satisfactorily accounted for. In the third lot they may belong 
to the Tetrarhynchi found in the stomach. 
The character of the stomach contents throws but little light on the 
nature of the intermediate host. The stomach of the first was proba- 
bly empty, at least there is no record of any stomach contents in the 
notes made at the time of collecting. In the second case, a half-grown 
female, the stomach was filled with half-digested menhaden ( Brevoortia 
tyrannus). The third host, which measured about 7 feet in length, had 
in its stomach a bonito ( Sarda sarda ), the operculum of a large fulgur, 
and a large quantity of sandy mud. There were several hundred Thy * 
sanocephala in the spiral valve of this shark. 
III.— DESCRIPTION OF THE SPEC' oS . ExV; r 3 D VI ONS. 
The original description, while, in the lignc ^ . r « : and care- 
ful investigations, faulty in some particulars, is sufficiently accurate to 
make identification of the species reasonably satisfactory. A re\ >. 
description is given in the U. S. Fish Commission Report for 1887. A 
brief, systematic description of the species is, therefore, all that is nec- 
essary in this paper. 
Scolex very small, about the same size in large as in small individ- 
uals, thus appearing minute when compared with the large cervical 
ruff or pseudoscolex of an adult; quadrangular in outline and pro- 
vided with four oblong bothria, each armed with two short, straightish 
hooks, and with a single anterior loculus in front of the hooks. 
Each bothrium is thus divided into two pits or loculi by a transverse 
partition, which also bears the hooks at its extremities. During life 
the bothria are very versatile, moving backward and forward singly or 
in either parallel or diagonally opposite pairs. The anterior loculus is 
somewhat circular in living specimens, semicircular or crescentic in 
alcoholic specimens (figs. 4 and 6). The posterior pit is oblong-elliptical 
in living, somewhat shorter and broader in alcoholic specimens. The 
borders of the bothrial loculi are thin, but supported at the edges by a 
band of dense epithelial tissue. The neck immediately behind the sco- 
lex is slender, short, and cylindrical, usually in living and always in 
alcoholic specimens contracted and concealed within the voluminous 
cervical folds. 
