[131] NOTES ON ENTOZOA OF MARINE FISHES. 849 



nearly erect, are moderately broad and abruptly recurved at the point. 

 In front of the basal enlargement the hooks are, in the main, slender, 

 sharp-pointed, and arcuate, from 0.022 mm to 0.033 mm in length, the spirals 

 about 0.02 mm apart, about eight booklets visible in each spiral. The 

 hooks, for the most part, are nearly erect. There are, however, on one 

 side of the proboscis, two longitudinal rows of hooks, which are stouter 

 than the hooks in the other longitudinal rows, and are strongly appressed, 

 the hooks in each row pointing toward the other row. This arrange- 

 ment seems to be very similar to that figured by Van Beneden for his 

 Tetrarhynchus minutus from Squatina angelus. These two rows of ap- 

 pressed hooks are flanked on the one side by a row of rather short 

 broad-based hooks, strongly recurved, and on the other by a row of 

 rather short arcuate hooks. The remaining hooklets do not differ from 

 each other either in size or shape. They are long, slender-pointed, 

 arcuate, nearly erect, and impart a characteristic bristly appearance to 

 the proboscis. The proboscides taper gently toward the apex, where 

 there is much less diversity both in size and shape of hooks than there 

 is farther back. 



The lateral vessels of the water vascular system remain plainly visi- 

 ble in an alcoholic specimen lightly stained with haematoxylon. The 

 body is short, broad, and much flattened. In the mature segments the 

 ova are collected in a mass at the bottom of an elongated clear space, 

 which begins at the marginal genital aperture near the anterior end, 

 runs directly to the median line, follows the latter to near the posterior 

 end, where it expands into the cavity in which the ova are lodged. 

 The cirrus was not observed. I have not been able to demonstrate the 

 position of the female genital aperture in the alcoholic specimens, but 

 am disposed to think that it is lateral, from the fact that, in a living 

 specimen, there were distinct median lateral apertures on the squarish 

 segments in front of the mature segments. 



Otobothrium, gen. nov. 



[otif, (orog, the ear.] 



Body articulate, taenireform, head separated from body by a neck. 

 Bothria two, opposite, lateral, each with two supplemental ciliated pits 

 at the posterior free angles. Proboscides four, terminal, filiform, armed, 

 retractile in neck. Reproductive apertures marginal. 



According to Diesing's classification this genus belongs to the sub- 

 tribe Trypanorhyncha and the family Dibothriorhynchidce. The number 

 of the bothria allies it with the genus Rhynchobothrium. On the other 

 hand the neck of Otobothrium bears a close resemblance to that of Tet- 

 rarhynchus. The reason for separating it from Rhynchobothrium and 

 erecting it into a new genus is found in the presence of the four otosacs 

 or ciliated pits. These, if not homologous with the supplemental disks 

 of Calliobothrium, etc., certainly famish a character of as much weight 

 in classification as they. 

 0, Mis. 133 54 



