TREMATODES 



181 



B. gracilescens (Rudolphi) (Fig\ 295). Length 1.4 mm.; width .5 

 mm.: in Tylusunis mariniis and other marine fishes; larva (Fig. 294) in 

 gonads and other organs of the oyster, often causing 

 death. 



Suborder 2. PROSTOMATA. 



Mouth at the anterior end, in the oral sucker; in- 

 testine bifurcate (with a few exceptions) : 4 divisions. 



Key to the divisions of Prostomata: 



tti But 1 sucker present 1. Monostomata 



02 Two suckers present. 



&i Acetabulum at hinder end 2. Ampiiistomata 



62 Acetabulum in ventral surface. 

 Ci Additional organs of attachment not present. 



3. DiSTOMATA 



C2 Additional sucking disc or projection present. 



4. HOLOSTOMATA 



Fig. 295 



Bucephalus 



gracilescens 



(Tennent). 



1, sucker ; 2, mouth. 



Other references 



as in Fig. 293. 



Division 1. MONOSTOMATA. 



Oral sucker alone present; arrangement of organs similar to that of 

 the Distomata: in vertebrates, especially birds and sea turtles; several 

 families. 



Family 1. CYCLOCCELIDAE. 



Large trematodes in which the intestinal trunks 

 join at the hinder end; genital pore in anterior half 

 of the body; ovary in front of testes: in the air 

 passages of birds; 6 genera. 



Cycloccelum Brandes. Intestinal trunks with- 

 out lateral branches; uterus entirely between the 

 trunks: 10 species. 



C. mutabile (Zeder). Body elongate, attenuate 

 forward and about 18 mm. long; testes small, the 

 hinder one near the juncture of the intestinal trunks : 

 in Gallinago and other birds. 



Family 2. PRONOCEPHALIDAE. 



Body usually elongate, with a collar-like rim 

 around the head; testes and ovary in hinder end of 

 body, the testes being in same transverse plane with 

 the intestinal trunks between them: in turtles. 



Pronocephaltjs Looss. With the characters of 

 the famil}^: several species. 

 P. renicapitis (Leidy) (Fig. 296). Length 25 mm.; width 3 mm.; 

 testes lobate : intestine of Sphargis coriacea. 



Fig. 296 — Prono- 



cephalus renicapitis 



(Braun). 



References 



as in Fig. 293. 



