PARASITIC FLATWORMS 



391 



78 (79) ' Uterus long and much coiled Echinostoma Rudolph! 1809. 



Echinostomes of moderate size with elongate body. Collar with double unbroken row of 

 spines. Oral and ventral suckers close together. Cirrus sac reaches ordinarily center of 

 acetabulum. Cirrus long, not spinous, when contracted it lies in coil. Vesicula seminalis 

 twisted, not bipartite. Pars prostatica present. Vitellaria lateral, posttesticular, extending 

 in places towards median line. Uterus long, much coiled. Eggs large. 



A mixed group of unplaced and unrelated species, many of which are not well enough known 

 to determine their, true place in the family. Several uncertain North American species are 

 reported under this generic name from chickens (Hassall), and muskrat (Leidy). Some forms 

 from the muskrat ace more perfectly described by Barker et alii. 



79 (78) Uterus short, coils few, open. 



Echinopharyphium Dietz 1909. 



Small echinostomes, slender. Much like last genus except in absence of pars prostatica. 

 Cirrus sac long, often extending dorsad, or posteriad to center of acetabulum. Uterus short; 

 eggs not numerous, large. 



The placing of Distomum flexum Linton from the black scoter (Yellowstone Lake) in this 

 genus is probably correct. Another species has been reported by Barker and Bastion from the 

 muskrat. 



80 (77) Spines in a single row. Subfamily ECHINOCHASMINAE Odhner 1910. 



Spines in a single row interrupted at the mid-dorsal line, with 20 to 26 

 spines only. Cirrus sac when present pyriform, not projecting behind 

 the center of the acetabulum . Vesicula seminalis not coiled, distinctly 

 bipartite. 



Several genera common in Europe. 



Only genus yet recorded from North America. 



Stephanoprora Odhner 1902. 



Small, elongate echinostomes, Cirrus sac well developed, cirrus short 

 but muscular, often apparently entirely preacetabular. Testes median, 

 close together, in posterior half of body. Vitellaria lateral, never pre- 

 acetabular, often nearly confluent along median line. Uterus not long; 

 eggs of moderate size. 



Representative American species. 



Stephanoprora gilberti Ward. 



The species reported by Gilbert from the loon (Gavia imber) and from 

 Bonaparte's gull (Larus Philadelphia) near Ann Arbor, Michigan, probably 

 belongs to this genus. It cannot be Echinostoma spimdosum Rud., as 

 designated. 



FIG. 678. Stephanoprora gilberti. X 7<x (Original.) 



8 1 (76) Oral sucker degenerate. Parasitic in gall ducts. 



Pegosomum Ratz 1903. 



Echinostomes of moderate size with lance-shaped muscular body. Collar poorly developed, 

 with single row of blunt spines. Skin spinous. Oral sucker entirely degenerate. Pharynx 

 present. Fork of intestine not near acetabulum which is powerful and near center of body. 

 Cirrus sac large, mostly preacetabular. Testes median, hi posterior half of body. Ovary 

 dextral, postacetabular and pretesticular. Vitellaria from pharynx to posterior end, confluent 

 in median line, only in front of genital pore. Uterus short. Eggs large, not numerous. 



In gall ducts of Ardeidae. Only one species reported from North America as Distomum 

 asperum Wright from Ardea minor. 



82 (75) Oral sucker without collar and spines 83 



A condition not represented in the key is found in the ACANTHOCHASMIDAE where the large 

 funnel-shaped oral sucker opens at the anterior tip and is surrounded by a crown of promi- 

 nent spines. Acanthochasmus coronarium (Cobbold) was taken from the alimentary canal of 

 an Alligator mississipiemis that died in England. According to Odhner Cryptogonimus and 

 Caecincola are members of this family which have lost the crown of spines. Deropristis may also 

 be related to it. 



83 (94) Genital glands median in linear series in posterior region of body. 84 



