42 PROCEEDINGS OF THE NATIONAL MUSEUM vol.81 



Genus CHIORCHIS Fischoeder, 1901 



Generic diagnosis. — Paramphistomatidae : Body ovoid, convex 

 dorsally and flat to slightly concave ventrally; anterior end some- 

 what attenuated, posterior end rounded ; ventral pouch absent. Oral 

 sucker with paired evaginations, usually retracted into an oral canal 

 by the action of strong muscles attached to the oral sucker; aceta- 

 bulum circular, near posterior end of body. Esophagus relatively 

 short, thick walled ; intestinal ceca terminate at middle of acetabular 

 zone. Excretory vesicle large, cephalad of acetabulum. Genital 

 pore at intestinal bifurcation, surrounded by a poorly developed 

 genital sucker; cirrus pouch absent; seminal vesicle much coiled. 

 Testes X shaped, tandem in position. Ovary posttesticular ; Mehlis's 

 gland dorsad of ovary; Laurer's canal opens dorsally in front of 

 excretory pore. Vitellaria extracecal, except near tips of ceca, where 

 a few follicles may be intercecal, and extending from a short distance 

 cephalad of intestinal bifurcation to level of anterior margin of 

 acetabulum. Uterus slightly sinuous, in median line dorsad of testes. 

 Eggs large, thin shelled. Parasites of Sirenia. 



Type species. — CMorchis fdbaceus (Diesing, 1838) Fischoeder, 

 1901. 



CHIORCHIS FABACEUS (Diesing, 1838) Fischoeder. 1901 

 Plate 10, Figures 41-45 



Synonym.. — A7iiphistomum fahacev/tn Diesing, 1838, p. 189 ; Schiz- 

 amphistonia nianati Sokoloff and Caballero, 1932, pp. 163-167. 



Description: — CMorchis: The body is ovoid in outline, 9 mm to 

 11 mm long by 5 mm wide, ventral surface flat or slightly concave, 

 dorsal surface strongly convex. The oral opening is slightly sub- 

 terminal and is followed by an oral canal, the length of which 

 depends upon the degree of retraction of the oral sucker. The oral 

 sucker is about 465/>(, to 800/i in diameter, strongly muscular, and pro- 

 vided with two muscular dorsal pouches. The oral sucker is usually 

 retracted so that its position is about midway between the intestinal 

 bifurcation and the anterior end of the body, the retraction being 

 due to contraction of about 30 muscular bands inserted into the 

 wall of the oral sucker, which radiate posteriorly and attach to the 

 body wall. The acetabulum is ventral, 1.3 mm to 1.8 mm in diam- 

 eter, situated near the posterior end of the body. The esophagus 

 is relatively long and thick walled, its posterior portion being thick- 

 ened to form a bulblike structure. The intestinal ceca are spacious 

 and thick walled and extend to about the center of the acetabular 

 zone. The excretory pore is situated in the mid-dorsal line slightly 

 cephalad of the level of the ovary; the excretory vesicle is pouch 

 shaped and relatively thick walled. The lymph system consists of 

 two longitudinal vessels which lie dorsally and medially of the 



