ART. 17 PAEASITES OF AMPHIBIA AND EEPTILIA HARWOOD 9 



and finally opens on the median, dorsal surface at the level of the 

 yolk reservoir. The extensive coils of the uterus fill the body pos- 

 terior to the genital field and to some extent invade the genital field 

 itself. In unflattened specimens they usually obscure the ootype and 

 Mehlis's gland and often extend laterad beyond the ceca. The eggs 

 measure 20-31/a by 38-44ju,. The vitellaria reach cephalad to the 

 middle of the oral sucker and caudad to the ends of the ceca. They 

 only slightly overlap the ceca and are mostly lateral to them. In 

 the esophageal region the vitellarian fields widen considerably. The 

 testes lie anterior to the ovary, but only slightly so. The testis of 

 the ovarian side is the more anterior of the two. They are some- 

 what irregular in shape, apparently because of pressure from the 

 intestinal ceca, the acetabulum, and the female genital system. They 

 are of approximately equal size and vary from 0.07 by 0.105 mm to 

 0.14 by 0.15 mm. The vasa efferentia leave from the medio-cephalic 

 corners and extend to the seminal vesicle in the cirrus sac. The 

 cirrus sac is about 0.15 mm long and runs caudad from the genital 

 pore, which is median and lies in the region of the intestinal fork. 

 A pars prostatica is present. The simple capillary excretory vesicle 

 extends from the terminal excretory pore to a point slightly behind 

 the seminrJ receptacle. 



Hosts. — Storeria dekayi, LeiolopisTna laterale, and Eunieces 

 fasd-atus. 



Habitat. — Intestine. 



Locality. — Houston, Tex. 



Type specimens. — U.S.N.M. Helm. Coll. No. 30868 ; paratype. No. 

 30869. 



Remarks. — This species is very similar to Mesocoel'min microon 

 NicoU (1914a) from Australian anurans. The chief difference is 

 that the esophagus is never longer than the pharynx in the present 

 species, while it is twice as long in the Australian form. The testes 

 are smaller relative to the acetabulum, and the ovary appears to be 

 slightly more anterior relative to this organ. The suckers, pharynx, 

 and eggs seem to be a little larger in my species than in NicoU's. 



The record for Eumeces fasclatus is based on a single individual, 

 which is so young that there is no indication of either eggs or 

 vitellaria. The ovaries and testes, however, are well developed and 

 occupy the same position relative to each other and to the acetabulum. 

 The ratios between pharynx, acetabulum, and oral sucker are iden- 

 tical with those for the mature specimens of Mesocoeli-imi ameri- 

 canum. In the specimen from Ewneces fasciatus., however, the 

 acetabulum is relatively farther posterior, being near the middle of 

 the body, and the intestinal ceca are distinctly longer when com- 

 pared with the length of the body. 



