52 PROCEEDINGS OF THE NATIONAL, MUSEUM vol.81 



OPISTHOTREMA COCHLEOTREMA (Travassos and Vogelsang-, 1931 «) new combination 



Plate 11, Figtjbb 47-49 



Synonyms. — AmpMstomum fdbaceum Diesing of Leicly, 1891, pp. 

 413-414, in part ; O pisthotrema cochleare Fischer of Stiles and Has- 

 sall, 1894, p. 253 ; Cochleotrema cochZeotreina Travassos and Vogel- 

 sang, 1931, pp. 143-146. 



Descriptio7i. — Opisthotrema: The body is oval in outline, 8.5 mm 

 long by 6.5 mm wide, strongly concave ventrally and convex dorsally ; 

 the margin of the body is surrounded by a more or less delicate 

 muscular rim, which is about 250/1 wide. The strongly convexo-con- 

 cave condition of the body suggests that the entire worm attaches 

 itself to the mucous membrane in the manner of a vacuum cup, the 

 muscular rim serving as a sort of seal. The cuticle of the ventral 

 surface is covered with scalelike spines, Yyu, long by 4/* wide, arranged 

 in irregular alternating rows. The excretory pore is situated dor- 

 sally, about 930/1, from the posterior end of the body, the aperture 

 being surrounded by a muscular sphincter. The excretory vesicle 

 is tubular, about 1 mm long, and is provided with two principal 

 branches on each side ; the first branch occurs at the level of the blind 

 ends of the ceca and the other at the anterior end of the vesicle ; two 

 smaller branches are given off on each side a short distance caudad 

 of the anterior branches. The remainder of the excretory system 

 could not be worked out in detail, but judged from sections the course 

 of the principal branches is probably similar to that described by 

 Fischer for O. cochleare. The oral sucker is transversely oval, 1 mm 

 long by 1.3 mm wide, strongly muscular, and situated ventrally about 

 465/A from the anterior margin of the body ; it is deeply imbedded in 

 the parenchyma and projects only slightly beyond the ventral sur- 

 face. The esophagus is slender and about 465/x long ; the intestinal 

 ceca are slender and serpentine, 155/x wide, the blind ends converging 

 toward the median line. Cirrus pouch slender, about 3 mm long 

 by 155/x wide at the level of the testes ; the walls are moderately thick 



» This species was described by the writer as new in the present paper, but while the 

 manuscript was awaiting publication a description appeared by Travassos and Vogelsang 

 (1931) of a species from Trlchcchns maiuttus which appears to be the same form. The 

 description given herein is from the writer's specimens. Some slight differences exist be- 

 tween this and the description given by Travassos and Vogelsang, but these differences 

 appear to be those of interpretation. Travassos and Vogelsang note that in their speci- 

 mens the ventral surface is covered with small papillae similar to those occurring on the 

 ventral surface of Gastrodiscus, and that Laurer's canal is present. In the specimens at 

 the writer's disposal the ventral surface is covered with small triangular, scalelike spines 

 (pi. 11, fig. 49) and no Laurer's canal is present. The absence of Laurer's canal is shown 

 in pi. 11, fig. 48, which is a reconstruction from serial sections. 



The writer does not agree with Travassos and Vogelsang as to the necessity of creating 

 a new genus for this species, since the differences between this species and the type of the 

 genus are too slight to warrant such action. 



