306 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 108 



mum breadth in the region of the stalk, then tapers off and ends 

 about half way between the terminations of the male genital organs 

 and the posterior end of the sac. 



The testes are located in the region of the stalk. They consist of 

 a fairly long, straight portion followed by a slightly coiled portion. 

 The vasa deferentia are long and highly tortuous tubes, nearly as 

 wide as the testes at their beginnings, but gradually diminishing in 

 thickness. Each of the male genital systems is enclosed in a loose 

 sheath or bag. In the sections one sees a noticeable space between 

 the testis or vas and the envelope that surrounds it. 



The colleteric glands, located anterior to the stalk, occur in the 

 same sections of the animal as those which include the testes. They 

 lie in the dorsal half of the visceral mass, rather close to the mesen- 

 tery, and, although simple in construction, are not indistinct. The 

 base of the gland forms a cavity which contains a coagulum. A 

 short duct reaches from this cavity to the surface of the visceral 

 mass, and its wall, as well as that of the cavity, consists of a layer 

 of tall columnar epithelial cells. The gland reaches to a depth of 

 about 140 microns below the surface of the visceral mass and extends 

 in a dorsoventral direction for a distance of about 180 microns. 



The specimens identified here as Galatheascus minutus agree with 

 the description of the type material in size, position of the stalk, 

 nature of the external cuticle, structure and position of the colleteric 

 glands, and in the general morphology and location of the male genital 

 organs. The fact that the mesentery of G. minutus is described as 

 extending from the anterior to the posterior end, while in our specimens 

 it is only about three-fourths as long as the sac, is not considered to be 

 a significant difference. Boschma (1933, p. 478) stated that the 

 testes of minutus have theu- closed ends directed "towards the posterior 

 extremity" of the body, but the word "posterior" in this connection 

 was a mistake (Boschma, personal communication) . In our material 

 and in the type specimens of minutus the blind ends of the testes point 

 in an anterior direction. This is lilcewise the condition in G. siriatus 

 (Boschma, 1929). Although the sac that suiTounds each of the male 

 reproductive systems is not mentioned in the description of the type, 

 Boschma's figures of transverse sections of striatus and minutus both 

 show this feature. 



The list of Peltogastridae occurring on the Galatheidae is now as 

 follows: Galatheascus striatus, G. minutus, Tortugaster Jistulatus, 

 Cyphosaccus chacei, C. cornutus, and Boschmaia munidicola. A com- 

 parison of the morphology of these animals fails to reveal any distinc- 

 tive feature that sets this group apart from the other Peltogastridae, 

 although in all except Galatheascus there is a pronounced tendency 

 toward asymmetry. 



