432 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
A single specimen collected July 30, 1900, was at first thought to be near D. fcecundum. The 
general habit of the body is much as in that species. The opening of the acetabulum, however, instead 
of being transverse, is longitudinal. It suggests also Beneden’s D. cestoides, but the testes appear to lie 
transversely near the posterior end instead of on the median line. As far as can be made out from an 
examination of the specimen in glycerine, it has the following characters: Body smooth, thickish, 
depressed, of nearly the same breadth throughout, rounded at each extremity; aperture of mouth nearly 
circular, a little wider than long; acetabulum much larger than oral sucker, aperture elongated; 
pharynx pyriform, with the larger end in front and overlapped by the oral sucker; oesophagus at least 
as long as pharynx; intestinal rami not clearly made out, but apparently. simple and reaching to the 
posterior end ; cirrus passes dorsal to the acetabulum to the right of the oesophagus as far as the pharynx, 
whence it curves back and opens at the anterior border of the acetabulum. Testes two, side by side 
near the posterior end; ovary smaller, apparently two-lobed, in front of testes and toward the left; uterus 
in front of testes in middle of body; ova of different sizes. Vitellaria two narrow clusters of small dark- 
brown bodies lateral to the testes, the one on the right extending less than halfway to the acetabulum, 
the other a little more than halfway. Dimensions in millimeters: Length, 7.5; breadth, 2; oral sucker, 
length 0.97, breadth 0.94, aperture 0.25 long and 0.28 wide; acetabulum, length 1.38, breadth 1.5, 
aperture 0.48 long and 0.33 wide; pharynx, length 0.44, greatest breadth 0.33; larger ova 0.086 and 
0. 045. smaller 0.062 and 0.035, in the two principal diameters. 
Tetronarce occidentalis, Torpedo. 
FOOD. 
The alimentary canal was nearly empty in all the torpedoes I have examined, a few remains of fish 
being about the only identifiable contents. The stomach and intestine in all cases, including one 
specimen examined in 1889 and two in 1900, contained an extremely viscid and tenacious mucus. 
The extraordinary thickness of the walls of the alimentary tract is apparently associated with equally 
extraordinary digestive power. 
CESTODES. 
1. Calyptrobothrium occidentale Linton. Spiral valve. 7,pp. 274-275 arid 298-299, pi. xli, figs. 92-97. 
July 29, 1899; 3 strobiles; scolices not found. July 16, 1900; 5, small, 20 to 27 mm. in length, 
only 1 with scolex. The changes wrought in the appearance of the^scolex of this species by 
different states of contraction are very diverse. 
2. Rhynchobothrium imparispine Linton. Larvae in cysts in intestinal wall. 7, p. 275. 
3. Tetrarhynchus bisulcatus Linton. 5, pp. 810-811, pi. lxvi, figs. 13, 14. 
Dasyatis centrura (Try yon centrum), Sting Ray. 
FOOD. 
The stomachs of the sting rays which I have examined have been, as a rule, empty. Fragments 
of Crustacea and annelids, however, have been found in most cases somewhere in the alimentary tract; 
small fish recorded in one instance. 
NEMATODES. 
1. Ascaris (?) . Immature. Spiral valve. 
A single specimen collected August 1, 1887. It is immature, has been introduced with food, and 
the sting ray may not be its proper host. Body smooth, of nearly uniform diameter, with fine 
longitudinal strife. Head with four blunt, rather obscure papillae. Tail slenderly mucronate. Some 
dimensions in millimeters: Length, 18; diameter of head, 0.08; length of oesophagus 1.12, diameter 
2 mm. from head atmiddle and 2 mm. from posterior end 0.22; diameter at anal aperture, 0.12; distance 
of anal aperture from posterior end, 0.16. The body enlarges slightly at base of oesophagus. 
CESTODES. 
All except encysted forms from spiral valve. 
2. Anthobothriurn pulvinatum Linton. [ Rhodobothrium pulvinatum, Am. Journ. Sci. and Arts, March, 
1889.] 2, pp. 759-765, pi. iv, figs. 4-9; pi. v, figs. 1-2. 5, pp. 439-440, pi. xxx, fig. 1. 7, 
p. 275. Aug. 24, 1899; 1; large, with large number of free proglottides. 
