PARASITIC FLATWORMS 433 



Genital pores median, ventral, approximated but distinct; cirrus pore most anterior. Cirrus 

 large, oval. Testes in lateral fields, dorsal. Vagina with vesicle near distal end. Ovary pos- 

 terior, ventral, transverse to main axis. Shell-gland dorsal, near ovary and posterior to it. 

 Uterus in lateral coils, approaching form of rosette. Ova 70 by 35 /JL. 



Adult in white pelican; larvae in muscles and body cavity of trout; Yellowstone Lake, 

 Wyoming. 



The name of this form cannot be accepted as Dibothrium is only a synonym of Bothrio- 

 phalns and the location of the genital pores rules this species out of that genus as at present 

 defined. Furthermore its exact position and true relationship must remain uncertain until 

 its structure is better known. 



23 (22) Two sets of reproductive organs in each proglottid. 



Diplogonoporus Lonnberg 1892. 



Very large cestodes parasitic in whales, seals, and occasionally in man. 

 The human parasite, D. grandis, is reported by Ashford and King from Porto Rico so it may 

 easily reach the southeastern coast of North America (see also Sparganum mansoni). 



24 (15) Genital pores of different proglottids found on both surfaces of 



strobila, alternating irregularly from proglottid to proglot- 

 tid. . Subfamily CYATHOCEPHALINAE Liihe 1899 2 5 



Scolex unarmed, variable in form, not longer than wide, with two median or one apical 

 sucking organ in form of acetabula. External proglottid limits not marked, or absent. Geni- 

 tal organs single in each proglottid; all pores median. Vagina and uterus open in common 

 female genital atrium provided with sphincter and located posterior to male pore. Adults in 



fishes. 



25 (26) Apical sucking organ single, undivided by transverse fold. 



Cyathocephalus Kessler 1868. 



Scolex with single apical sucking organ in form of a cup, and without evidence in shape or 

 structure of its origin from fusion of two bothria located on surface. Proglottid limits distinct 

 externally. Sphincter of female genital atrium poorly developed. 



Adults in fishes. 



Type species Cyathocephalus truncalus (Pallas) 1781. 



Reported by Linton from pyloric ceca of common whitefish, Lake Superior. 



26 (25) Apical sucking-organ single but divided by transverse fold indicating 



its double origin. . . . . . Bothriomonus Duvernoy 1842. 



Scolex large, approximately spherical, with single apical sucking organ like acetabulum, 

 yet divided transversely by a fold which indicates its origin from two bothria typical of family. 

 No external proglottid boundaries. Sphincter of female genital atrium well developed. 



In Acipenser oxyrhynchus; Wabash River, Indiana. 



Type species Bothriomonus sturionis Duvernoy 1842. 



27 (14) Genital pore at margin of proglottid. 



Subfamily TRIAENOPHORINAE Liihe 1899. 



Scolex always with typical bothria, not very deep; flattened apex of scolex projects above 

 bothria as a more or less distinct annular cap. Marginal genital pores alternating irregu- 

 larly; uterine pore, median on ventral surface, anterior to marginal genital pore. Repro- 

 ductive organs single in each proglottid. No muscular bulb at inner end of cirrus sac. Re- 

 ceptaculum seminis small. Uterus in coils, but never in rosette form, somewhat enlarged near 

 its terminus. 



Adults in intestine of fishes and marine turtles; larvae in fishes, mostly unknown. 



Type genus Triaenophorus Rudolphi 1793. 



Scolex with 4 three-pointed hooks. No external proglottid markings. Testes occupy all 

 medullary layer not taken by other organs. Vitellaria continuous in cortical layer, interrupted 

 only at genital pores. Ovary and shell gland adjacent to margin bearing genital pore. Uter- 

 ine pore usually not median but on surface at right of median line when marginal pore is sinis- 

 tral and vice -versa. 



Adults in intestine of fishes; larva encysted in fishes. Present in North America; no spe- 

 cies definitely recorded as yet. 



