TiENIOID CESTODES OF NORTH AMEEICASI BIRDS, 101 



Genus DIPLOPOSTHE Jaeobi, 1896. 



Generic diagnosis. — Tsenioidea : Closely related to the Acoleidse 

 (according to Fuhrmann, 1907a, p. 294; 1908a, p. 85). Scolex with 

 rostelliim armed with a single crown of ten hooks. Suckers unarmed. 

 Inner longitudinal muscle layer, except for two or three small bundles 

 in the lateral portion beyond the excretory vessels, developed only 

 in the median portion of the segment, consisting of about ten dorsal and 

 ten ventral bundles of unequal size. Outer longitudinal muscle layer of 

 numerous equally developed bundles, interrupted only at the sides 

 where the genital canals pass through. Outside the outer longi- 

 tudinal layer a thin layer of diagonal fibers, and at the posterior end 

 of the segment a well-developed muscle ring. Genital pores marginal, 

 one on each side of the segment. Testicles few (3 to ? 7) , in the pos- 

 terior portion of the segment. Vasa efferentia unite to form two vasa 

 deferentia. Seminal vesicles present. Cirri two, one on each side of 

 the segment, armed with strong hooks. A single set of female glands 

 in the median field. Ovary bilobed; behind it, near the posterior 

 border of the segment, the yolk gland. Two vaginae. Uterus sac- 

 like, transversely elongated, with large diverticula, which push 

 through the musculature dorsally and ventrally, and also extend 

 forward to the anterior border of the segment. Eggs with three thin 

 transparent envelopes. Adults in birds. 



Type-species. — Diploposthe Iscvis (Bloch, 1782, of Diesing, 1850) 

 Jaeobi, 1896. 



DIPLOPOSTHE L^ffiVIS (Bloch, 1782) Jaeobi, 1896. 



For description see Krabbe, 1869b, pp. 302-303, pi. 7, figs. 165-167 ( Tsenia Isevis).— 

 Jacobi, 1897a, pp. 287-306, pis. 26, 27.— Cohn, 1901b, pp. 421-430, pi. 35, figs. 

 81-85.— Fuhrmann, 1905a, pp. 217-224. 



Hosts. — Clangula clangula, Marila rnarila, Netta rujina, Spatula 

 clypeata, Nettion crecca, Chaulelasmus streperus, Anas ruhripes, Anas 

 platyrhynchos , Anas platyrhynchos domestica, Branta canadensis. 



Family ACOLEID^ (emended name) . 



Acoleinx Fuhrmann, 1900. 

 "Acoleinidae" Fuhrmann, 1907. 



Family diagnosis. — Tsenioidea: Scolex generally armed, seldom 

 without rostellum. Suckers unarmed. Strobila thick, with short 

 segments. Musculature consists of at least two layers of longitudinal 

 muscles alternating with layers of transverse muscles. A single set, 

 double set, or partial duplication of reproductive organs in each seg- 

 ment. Male genital openings marginal. Female genital (vaginal) 

 openings lacking. Cirrus always very large and armed with strong 

 hooks or spines. Egg with thin transparent shells. Adults in birds. 



Type-genus. — Acoleus Fuhrmann, 1899, 



