56o 



TREMATODA 



that the cat, the dog, the pig, and cattle are indirect sources 

 of infection, while bathing, wading and drinking water as well as 

 green vegetables, particularly those not cooked, must be regarded 

 as definite sources of infection, and so must that delicacy the edible 

 snail, which may not be properly cooked. 



Classification, — The classification of the Trematoda is as follows :• — 



SUBCLASS I. HETEROCOTYLEA Monticelli. 



Synonyms— Poly stomea Leuckart, Pectobothrii Burmeister, and 

 Monogenea van Beneden. 



These Trematodes are generally ectoparasitic, but may be endo- 

 parasitic in amphibia and tortoises. 



SUBCLASS II. ASPIDOCOTYLEA Monticelh. 

 Synonym. — A shidobothrii Burmeister. 



These are lowly organized endoparasitic trematodes, with one 

 large sucker occupying the whole ventral surface, found in tortoises, 

 marine fish, and shellfish. 



SUBCLASS III. MALACOCOTYLEA Monticelh. 



Synonyms. — Distomea Leuckart, Malacobothrii Burmeister, and 

 Digenea van Beneden, 1858. 



Definition.^ — -Typical endoparasitic trematodes, with never more 

 than two sucking-discs, oral and ventral, and a Laurer's canal. 



Remarks.- — -The Malacocotylea include all the human trematode 

 parasites. 



Classification. — -The Malacocotylea may be divided into orders 

 as follows : — ■ 



A. Development without alternation of generations— Order i, 



Monogenea van Beneden, 185S. 



B, Development with alternation of generations— Order 2, 



Digenea van Beneden, 1858. 



We are only concerned with Order 2. 



ORDER DIGENEA van Beneden, 1858. 



Definition. — Malacocotylea with a single median anterior sucker, 

 a vagina, and few eggs which develop by alternation of generations. 



Classification. — This order is divided into several suborders, of 

 yNhich Prostomata concerns us. 



Mouth surrounded by the anterior sucker^ — Suborder Pro- 

 stomata Odhnei, 1905. 



Suborder Prostomata Odhner, 1905. 



Definition.' — Digenea, in which the mouth is surrounded by the 

 anterior sucker. 



Classification.— The Prostomata are divided into superfamilieS/ 

 in the following manner : — 



