192 PROCEEDINGS OF THE NATIONAL MUSEUM vol. loi 



can be readily distinguished by the manner in which its fairly wide 

 ceca pass medially to the testes and vitellaria, and in having the com- 

 mon collecting tubules of the excretory system pass dorsal to the 

 medial margins of the testes. 



ZONORCHIS PETIO LATUM (Railliet, 1900), new combination 



Figure 40, a-(Z 



Dicrocoelium petiolatum Railliet, Comp. Rend. Soc. Biol., vol. 52, p. 241, 1900. i, 

 Eurytrema sp. Denton, in Petri, Trans. Amer. Micr. Soc, vol. 61, p. 61, 1942. '. 

 Lyperosomum petiolatvm Travassos, Monogr. Inst. Oswaldo Cruz, No. 2, pp. 136- - 

 137, est. 45, figs. 3-6, 1944. 



Description: Body spindle-shaped when relaxed, fairly thick and ] 

 muscular, 2.26 to 4.18 mm. long by 0.34 to 0.92 mm. wide, widest in i 

 region between testes and ovary. Cuticle without spines and with i 

 small retractile sensory papillae, which are more visible on margins of 1 

 anterior half of body. Oral sucker muscular, 0.13 to 0.20 mm. in i 

 diameter, subterminal in position and preceded dorsally by a fairly ' 

 prominent liplike projection. Acetabulum muscular, with deep cup- 

 shaped lumen, much larger than oral sucker, 0.25 to 0.40 mm. in 

 diameter, situated within anterior fourth of body. Ratio of diameter 

 of oral sucker to acetabulum varying from 1 :1.7 to 1 :2.19. Pharynx 

 globular, 0.05 to 0.10 mm. in diameter. Esophagus narrow, usually 

 straight, 0.10 to 0.13 mm. long, surrounded by minute gland cells. 

 Esophagus bifurcating one-half to two-thirds the distance from oral 

 sucker to acetabulum. Ceca slender and slightly sinuous, passing 

 dorsolaterally to margins of testes, terminating approximately one- 

 half the distance from vitellaria to posterior end of body. Excretory 

 pore terminal. Excretory vesicle tubular and voluminous, extending 

 anteriad almost to Mehlis' gland, receiving a common collecting tubule ' 

 from each side of body. Each common collecting tubule passing ( 

 anterolaterad to level of equator of testes where it branches into an i 

 anterior and posterior main collecting tubule. Genital pore median 

 at about posterior level of pharynx. Testes rounded, 0.09 to 0.20 mm. 

 in greatest diameter, situated directly opposite with zones contiguous 

 or partly overlapping that of acetabulum. Cirrus sac club-shaped, , 

 0.14 to 0.21 mm. long by 0.05 to 0.06 mm. wide, lying entirely in front 

 of or partly dorsal to anterior margin of acetabulum, containing con- 

 voluted seminal vesicle, prostatic gland cells, and eversible cirrus. 

 Ovary round to transversely oval, 0.08 to 0.20 mm. in long axis, , 

 situated to either right or left side of body, relatively close behind t 

 testis on ovarian side of body. Seminal receptacle globular, located 

 dorsal to caudal margin of ovary. Mehlis' gland situated at postero- 

 medial margin of seminal receptacle. Vitellaria composed of numer- 

 ous medium-sized follicles, extending along lateral margins of body 

 for a distance of 0.85 to 1.32 mm., beginning within testicular zone and 



