292 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



Sections of both the large and the small specimens were made, and while it does not enter into 

 the plan of this paper to give histological details, the following anatomical details may be here 

 recorded for purposes of identification: The cuticle is thick, particularly its inner layer, which 

 presents a crenulate outline. Both longitudinal and circular muscles strongly developed, especially 

 the former, and in the neck transverse fibers are very abundant. The submuscular cell layer is very* 

 conspicuous. The pharynx is about half the length of the oral sucker, and opens*into the intestinal 

 rami by a very short (esophagus. The acetabuluui is strongly developed, and evidently functions as 

 a powerful suctorial organ. In all the specimens sectioned it had drawn in a part of the tissues con- 

 stituting the ventral portion of the base of the neck, Avhile the cavity of the acetabuluui contained 

 material which appeared to be pieces of the intestinal mucous membrane of the host. The branches 

 of the intestine lie dorso-laterally, and reach to the posterior end of the body. On account of the state 

 of contraction of the body, the intestinal walls are much convoluted. The cells lining the intestine 

 are large and the ends turned toward the lumen are swollen and stain very slightly with carmine. 



The excretory vessels were traced forward to the oral sucker and back to the posterior end, where 

 they unite. The vessels are large, their walls thin, granular inner surface staining deeply with 

 carmine. Near the posterior end the walls become somewhat thickened and appear much folded. 

 The ovary is in front of testes, toward the dorsal side and close behind the acetabuluui. Sonic of the 

 sections indicate an obscurely lobed structure. The shell gland lies on the ventral side of the ovary 

 and immediately behind the acetabuluui. The uterus, beginning at the shell gland just behind the 

 acetabulum, lills the posterior part of the adult body with its voluminous folds. It leads forward on 

 the dorsal side of the acetabuluui, and in front of that organ passes ventrally beside the cirrus pouch, 

 the external genital aperture being on the ventral side of the neck, a little to the right of the median 

 line in one specimen, a little to the left in another, and, as near as could be determined in these highly 

 contracted specimens, approximately about the anterior third of distance between the two suckers. 

 The testes are two, laterally placed behind the ovary and ventrally, and near enough so that some 

 of the transverse thin sections of the body passed through both the testes and the ovary. 



The seminal vesicle lies immediately in front of the acetabulum. It is inclosed in a spherical 

 muscular sac, but it and the vas deferens, cirrus, and prostate gland all are inclosed in a special sac. 

 This is partly shown in the sketch, fig. 49, p. sv. No posterior seminal receptacle was made out. 



The vitelline glands are conspicuous voluminous organs lying laterally and posteriorly rather 

 more ventral than dorsal. They appear to consist of numerous branching glands which extend 

 forward to the posterior edge of the acotabulum. In sections stained lightly with carmine these organs 

 are beautifully differentiated as golden-brown bodies with parts stained red with the carmine. Both 

 ovary and testes stain strongly in carmine. 



Distomum pyriforme sp. nov. 

 [Plato 38, figs. 52-59, U. S. K. M. No. 6516.] 



These distoma were found on four occasions, August 10, 19, 22, 25, in enormous numbers in the 

 pyloric ca;ca of the rudder-fish (Palinurichthys perdformis}. 



Body very slightly compressed, of various shapes, but usually elliptical or pyriforui in outline, 

 armed with low, flat, rounded, scale-like spines. Neck in some slightly extended; in others the oral 

 sucker was retracted (fig. 56). Mouth subterniiual, orbicular. When the worm is extended so as to 

 give a favorable view the oral sucker is slightly elongated and separated from the pharynx by a short 

 oesophagus. The latter, of course, is difficult to make out in contracted specimens. Acetabulum a little 

 broader than long, about equaling the oral sucker and situated about the middle of the length of the 

 body. Intestinal branches conspicuous, straight, reaching to the posterior end of the body. Testes 

 two, nearly globular, but breadth slightly greater than length in elongated and considerably greater 

 in contracted specimens, situated w r ell toward the posterior end, close together, one immediately in 

 front of the other. Cirrus pouch elongated, on right side of acetabulum opening in front of the 

 same; cirrus spinose. Ovary small, round, situated in front of the testes near the seminal vesicle, 

 dorsal, and a little toward the right and close to the acetabuluui. Vitollaria voluminous, filling the 

 greater part of the body, especially at the posterior end and along the lateral margins as far forward 

 as the acetabulum. Uterus evidently short, ova very few and relatively. large, lying between ovary 

 and acetabulum and equaling in length the diameter of that organ. 



