294 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



The reproductive aperture is in front of the acetabulum. The ovary is subglobular and lies on 

 the left of the median line and is separated from the acetabulum by the uterus with a few three or 

 four large ova, and the shell gland. The latter lies just back of the acetabulum. On the right side 

 of the median line and at about the same level as the ovary is the posterior seminal receptacle. Just 

 back of the seminal receptacle and ovary, and lying across the median line, is a lozenge-shaped mass 

 of vitelline substance, apparently a yolk reservoir, with ducts leading to the right and left to the 

 voluminous vitellino glands. These glands occupy the lateral margins of the body from the posterior 

 end to the pharynx. 



Dimensions in millimeters: (1) In sea water, length variable, but from 0.7 to 0.9; breadth 0.1; 

 oral sucker, length 0.10, breadth, 0.12; acetabulum, length 0.10, breadth 0.09; ova, longer diameter 

 0.11, shorter diameter 0.07. (2) Specimen mounted in balsam, length, 1.3; greatest breadth 0.64; 

 diameter of oral sucker 0.17; diameter of acetabulum 0.13; length of pharynx 0.28; breadth of same, 

 0.2;") ; distance between suckers (margins) 0.14. In one case where the acetabulum was 0.10 long and 

 0.11 broad, an ovum measured 0.117 and 0.076 in the two principal diameters. 



* 



Distomum deiitatum sp. nov. 



[Plate 39, figs. 04-67, IT. S. N. M. No. or.lK.] 



A few small distoma from the flounder (Paraliehthya dtnitatux), resembling in many important 

 particulars the species which I have called />. tcntic (Proc. U. S. Nat. Mus., vol. xx, p. 535, pi. MI, ligs. 

 2-8), are here included. 



The following description is based mainly 011 specimens mounted in balsam: Body somewhat 

 depressed, increasing in breadth toward posterior end, the proportions varying with different stages 

 of contraction, but posterior end usually bluntly rounded, greatest diameter usually at the posterior 

 testis; neck short, conical, cylindrical in front, somewhat depressed at base; neck and body covered 

 with short, subtriangular, scale-like spines, which are densely placed anteriorly, but become scatter- 

 ing at posterior fourth and very sparse at posterior end; ventral sucker sessile, larger than oral 

 sucker, nearly circular in outline, with transverse aperture, situated about the anterior third, though 

 in some cases where the neck Avas contracted the suckers were closer together and the acetabulum 

 was then in advance of the anterior third ; mouth terminal, surrounded by double circle of straightish 

 spines, about 24 in each circle, the spines of one circle alternating Avith those of the other; the 

 oblong pharynx is separated from the oral sucker by a distance approximating its own length, lies 

 close to the front edge of the acetabulum, and opens directly into the intestine. 



The branches of the intestine extend to the posterior end of the body. The cirrus pouch, with 

 the inclosed seminal A^esicle, lies behind the acetabulum and a little to the right. The cirrus passes 

 along the right dorsal edge of the acetabulum, Avhile the distal end of the uterus passes on the dorsal 

 left edge of the same", both coming together at the reproductive aperture in front of the acetabulum, 

 about on the median line. Behind the cirrus pouch and in front of the ovary is the uterus, containing 

 a comparatively small number (40 estimated in one) of OA r a. The OA-ary lies a little to the right of 

 the median line, immediately in front of the anterior testis, appearing somewhat triangular in outline. 

 The testes are tAvo, large, quadrangular in outline, broader than long, median, approximate, the 

 junction between them not far from posterior third of the body. The vitellaria are very abundant, 

 massed posteriorly, along the lateral margins even into the neck, and around the periphery of the 

 body over the other organs. 



Dimensions, in millimeters: 



(1) Living specimen: Length 1.14, anterior diameter 0.14, median breadth 0.37, diameter of oral 

 sucker 0.08, diameter of acetabulum 0.14, longer diameter of ovum 0.07, shorter diameter of ovum 0.03. 



(2) Specimen mounted in balsam: Length 1.85, anterior diameter 0.17, greatest breadth 0.64, 

 diameter of oral sucker 0.14, diameter of acetabulum 0.20, length of pharynx 0.14, diameter of pharynx 

 0.10, length of anterior testis 0.21, length of posterior testis 0.28, breadth of each testis 0.31, longer 

 diameter of ovum 0.06, shorter diameter of ovum 0.03, length of longest oral spines 0.04. 



When these specimens are compared Avith D. lenur, besides being considerably smaller they are 

 relatively broader and much more appressed. The number of oral spines is different, although this 

 difference should not be made much of, since observations on a great number of specimens are needed 

 to determine Avhat variations, if any, occur in this respect in these species. 



