AVIAN CESTODES. 



441 



variations in the longitudinal musculature are by no means 

 always accompanied by other structures which nnply undoubted 

 generic difference among the Oestodes. It is possible, however, 

 that a simple sac-like form of uterus characterises Ichogenes^. 



I should be, on the whole, disposed to define the genera of the 

 subfamily Idiogeninse as follows :— 



Subfamily Idiogenin^. 



A single paruterine organ present in the ripe proglottid. 



A. Ten to twelve \ 

 roivs of hooks on ■{ 

 the rostellutn. 



/ Sphyronchot^enia. — Suckers unarmed 

 I Genital pores unilateral. Longitudinal 

 I Qiiusdes thick. Dorsal water-vascular 

 trunk absent in 2^osterior j)roglottids. 

 Testes numerous, extending far anteriorly. 

 Uterus divided into chambers, larger than 

 I joa?-Mfe?'Mie organ. Eggs transferred late 

 ^ to pariUerine organ. Cirrus-sac small. 

 (OriDiTyENiA. — Suckers unarmed. Genital 

 pores alternate. Longittidinal muscles 

 thick. Dorsal loater-vascidar trunk present 

 in p)osterior segments. Testes numerous, 

 posterior. Uterus divided into chambers, 

 extends dorsally into cortical layer, much 

 smaller than 2Jciriite7nne organ. Eggs 

 transferred late to |x«-Mierme organ. 

 Cirrus-sac small. 

 GHAPMANJAf. — Suckers armed. Genital 

 pores alternate. Longitudinal muscles 

 thick. Dorsal water-vascidar vessel absent 

 in posterior proglottid. Testes mwierous, 

 posterior. Uterus divided into chambers, 

 which in mature uterus commimicate and 

 form a network, larger than 2Jaruterine 

 organ. Eggs transferred early to paru- 

 terine organ. Cirrus-sac large. 

 Idiogenes+. — Suckers unarmed. Genital 

 pores unilateral or alternate. Longitio- 

 dinal muscles slight. Testes few, pos- 

 terior. Uterus not divided into chambers, 

 larger than 2Mcruterine organ. Cirru,s-saG 

 y t?ery large. 



* See also footnote to p. 438 for another possible generic distinction. 



+ In^^ew of the network which the sperm-duct forms and the tentacles upon the 

 crolex I exclude for the present C. tapica from the above genus. 



+ It wm be noted that the feebly developed longitudinal muscular system the 

 smtu number of testes, and the simplicity of the uterus may be correlated with the 

 small size of the species of this genus. 



B. Two roius of \ 

 hooks on the ros- ■{ 

 tellum. 



