NO. 3 manter: a new genus of distomes 15 



Apocreadium longisinosum, new Species 



(Plate 2, figs. 4-7) 



Hosts: Cheilichthys anmilatus (Jenyns) 



Albermarle Island and Charles Island, Gala- 

 pagos Islands 



Spheroides angusticeps (Jenyns) 

 Charles Island, Galapagos 



Position: rectum 



Incidence: 2 to 10 in a host, total of 15 collected from 

 3 hosts. 



The body is orange-yellow in its posterior half, unspined, more 

 or less flattened, 6.57 to 9.65 by 1.552 to 2.403 mm., widest about 

 at midbody, tapering toward each end. A 4.650 mm. specimen was 

 immature. The posterior third of the body is thin and flexible with 

 numerous lateral folds. It tapers sharply to a pointed posterior end. 

 The anterior half of the body is more plump, smooth, and tapers 

 gradually. A small, fleshy preoral lobe is present. The oral sucker 

 is subcircular but usually slightly longer than wide, 0.375 to 0.532 

 mm. in transverse diameter. The acetabulum is about % body 

 length from the anterior end, is longer than wide, 0.675 to 0.885 

 mm. in transverse diameter. Its aperture is longitudinal. The sucker 

 ratio is approximately 5:8. The forebody measures 1.360 to 2.430 

 mm. 



There is a fairly short prepharynx (about >^ pharynx length). 

 The pharynx is usually somewhat pyriform in shape. The anterior 

 third is more narrow, provided with a larger number of circular 

 muscles, and separated from the posterior region by a very slight 

 constriction. Muscles extend from the oral sucker to the pharynx 

 outside the prepharynx. The esophagus is approximately the same 

 length as the prepharynx. The intestinal bifurcation is usually a 

 little nearer the oral sucker than the acetabulum but it may be ap- 

 proximately midway between the suckers. The narrow ceca extend 

 some distance in from the body margins to within a short distance 

 of the posterior end. They do not reach the posterior end and may 

 fail to do so by some distance. One curious abnormality involved 

 the left cecum which was almost completely degenerate except for 

 a short normal-appearing stub barely reaching beyond the bifurca- 

 tion and ending abruptly. The remainder of the cecum was repre- 

 sented by a few strands of fine fibrous tissue. 



