TEEMATODES 



181 



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

 mm.: in Tylosurus marinus 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: 



01 But 1 sucker present 1. MONOSTOMATA 



2 Two suckers present. 



&! Acetabulum at hinder end 2. AMPHISTOMATA 



& 2 Acetabulum in ventral surface. 

 Ci Additional organs of attachment not present. 



3. DlSTOMATA 



c, 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. PEONOCEPHALIDAE. 



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. 



PRONOCEPHALITS Looss. With the characters of 

 the family: several species. 

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

 testes lobate : intestine of SpTiargis coriacea. 



Fig. 296 Prono- 



cephalus renicapitis 



(Braun). 



References 



as in Fig. 293. 



