RHIZOCEPHALA — REINHARD 299 



its course to open alongside the testes at the junction of the mesentery 

 with the mantle. 



The single specimen from the Barbados (fig. l,d) was not sectioned. 

 It appears to be an animal that is undergoing degeneration after the 

 release of its brood. The mantle cavity is empty and the anterior 

 end of the sac has a conspicuous round orifice, presumably the bh-th 

 pore. The host also bears the scar of a companion parasite no longer 

 present. 



Remarks: Dr. Fenner A. Chace, Jr., curator of marine inverte- 

 brates, U. S. National Museum, for whom this species is named, 

 recorded the presence of abdominal parasites on three examples of 

 Munida irrasa A. Milne Edwards obtained by the Atlantis off Cayo 

 Coco, Cuba (Chace, 1942, p. 46). Two of these were loaned to the 

 author through the courtesy of the Museum of Comparative Zoology. 

 They provided part of the material described here. 



Cyphosaccus corniitiis, new species 



Figure 2; Plate 1, Figure 2 



Syntypes: Off Playa Baracoa, Havana, Cuba, Atlantis Station 

 3305, lat. 23°05'30" N., long. 82°35' W., 330 fathoms. Mar. 23, 1939, 

 three specimens on one Munidopsis erinacea (A. Milne Edwards), 

 Harvard -Havana Expedition, Atlantis. MCZ 11721. 



Diagnosis: Body broadly U-shaped, comparatively stout, uniform 

 in thickness, with the stalk in the midregion. Testes fused. 



Description: The parasites are attached to the sternites of the 

 third and fourth abdominal segments. Two are oriented with the 

 anterior arm towards the left side of the host; the other is turned in 

 the opposite direction. All three are of approximately the same 

 size, 8 mm. in length and about 1 mm. in thickness. 



The shape of the sac resembles an ox-bow, although the anterior 

 arm is misshapen. The tip of this arm bears a nozzle-like prominence 

 enclosing a blind canal. The smooth external surface of the sac is 

 covered with a thin cuticle through which an underlying meshwork 

 of delicate longitudinal and circular muscle fibers belonging to the 

 mantle can be seen. The longitudinal fibers are more widely spaced 

 than the circular ones. 



When the animal is examined with the anterior arm to the observer's 

 left, as in the drawings, the mesenterial surface lies uppermost. The 

 mesentery, which extends along the entire length of the sac, supports 

 a well-developed visceral mass. In the animals that were sectioned, 

 segmenting eggs are also present in the mantle cavity. Whether 

 they hatch as nauplii or as cypris larvae is not known. 



