[63] NOTES ON ENTOZOA OF MARINE FISHES. 781 



DlSCOCEPHALUM * gen. DOV. 

 \_AiaKoq, a quoit.] 



Body articulate fcenireforin. Head composed of two parts. Tlie 

 anterior part a muscular disk, which is eutire or notched at the edge. 

 The posterior part (neck), short, globose, with an inflated or corrugated 

 surface. Neck (unsegmented part of body) much narrower than head 

 continuous with the body. No supplemental disks. Genital apertures 

 marginal. 



This genus is established to accommodate some peculiar cestoids from 

 the spiral valve of the dusky shark (Garcharias obscurus.) 



No indication of true bothria nor of supplemental disks was found 

 either in the living specimens or in preserved specimens made trans- 

 parent with glycerine or oil of cloves; nor could any such indication 

 be found in a series of sections of the head. 



On account of the small amount of material and the unsatisfactory 

 results of my study of it, I have determined to put this geuus in the 

 family Tetrabothriidce for the present. If my interpretation of the 

 homologies of this form is correct, it should be put in a new family, for 

 which the term Gamobotliriidce, also suggested for the problematic 

 genera Lecanicephalum and Tylocephalum, would be fitting. 



14. Discocephalum jiileatum gen. et sp. nov. 

 [Plate x, figs. 1-7.] 



Head, a transversely-flattened apical disk, entire, or with a single lat- 

 eral notch, followed by a much smaller, globular, inflated, cervical mass, 

 with botryoidal or corrugated surface, yellowish in color, and sepa- 

 rated from the apical disk by a narrow, orange-colored band, unseg- 

 mented part of body narrower than head merging into segmented body. 

 Anterior segments very short, much crowded; subsequent segments 

 longer than broad ; mature segments irregularly squarish, very change- 

 able in living specimen. Strobile flat, increasing in breadth uniformly 

 to the begiuning of mature segments, beyond which point it is some- 

 what narrower. 



Genital apertures marginal a little in front of middle, male and 

 female ai)proximate. Cirrus long and slender, vagina opening in front 

 of cirrus. 



Length, maximum 530 mm ; diameter of anterior disk 3 to 5 mm ; great- 

 est breadth of body 3 to 5 mm . 



Habitat. — Carchar las obscurus, spiral valve. Wood's Holl, Massachu- 

 setts, July 19, 1886. One adult, three young. 



In the single lot of specimens which furnishes the data for this 

 description there are two distinct varieties. 



* This genus is put provisionally in the family Tetrabothriidou 



