688 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



ASTACOBDELLA Philadelphica Leidy. 



Proceeedings of the Academy of Natural Sciences of Philadelphia, vol. v, p. 209, 

 1851. 



Dr. Leidy's description is as follows : " Body whitish, traaslucent ; 

 sides nearly parallel, a little broader posteriorly, 16 alternately broad 

 and narrow segments, exclusive of head and posterior end. Head cam- 

 panulate, terminated by a circular or elliptical crenated lip, fringed with 

 very minute stiff hairs, one two-thousandth of an inch long." 



"Acetabulum circular, one sixth to one-fourth of aline in diameter; 

 mouth elliptical. Dental plates brown, nearly equal, forming an isosceles, 

 triangle, with the base longest and attached. Apex of superior plate end- 

 ing in a sharp conical point ; with several very minute denticulations on 

 each side. Apex of inferior plate bifurcated into two points, with two 

 minute denticulations on each side. Stomach capacious, nearly filling 

 the anterior eight alternately broad and narrow segments posterior to 

 the head. Anus dorsal, one-fifth of a line from the acetabulum. Gen- 

 erative aperture ventral, anterior to the anal aperture. 



"Length, one to four lines; breadth, one-sixth to one-half of a line. 

 Head, one-sixth to one-half of a line long. Ovum attached by a pedicle, 

 with an operculum pointed at summit. From base of attachment to 

 point of opercle, one-fifth of a line. Length of body of ovum, one-sixth 

 of a line : breadth, one-eighth of a line. 



'■^Habitat. — Found frequently in numbers from one to several dozen 

 upon any part of the exterior of the body of Astacus Bartonii Fab., 

 but more especially upon the inferior surface and the branchiaB." 



The following species, which I have not seen, have been described 

 from North America : 



LiosTOMUM coociNEUM Waglcr. 



Isis, 1831, p. 533 ; ibid., 1832, p. 53 ; Diesing, Sitzungsb. der kais. Akad. der Wis- 

 senschaften, xxxiii, p. 495, 1859. 



This genus is remarkable in having no ocelli, and no folds, lobes, nor 

 plications within the mouth and cesophagus. 

 Mexico — Kar win sky. 



HiRUDO ORNATA Ebrard. 



Nouv, Monog. Saugs., p. 55. 

 Northwestern America. 



HiRUDo(?) CosTARiCENSis Grubs and (Ersted. 



Diesing, op. cit., p..509. 



Costarica — CErsted. 

 HiRUDO BiLLBERGHi Kinberg. 



Op. cit., p. 356, 1867. 

 This species is described as having eight ocelli, with the genital orifice 

 in the twenty-eighth segment. It probably belongs to some other genus. 



