No. 431.] MORTH-AMERICAN INVERTEBRATES. 897 
f, Acetabulum small; testes ovoid: in turtles 
Rhytidodes Lss. (Fig. 36) (49) 
f; Acetabulum very large; testes reniform: 
in Spilotes pullatus, a Brazilian snake 
Cotylotretus Odh. (Fig. 130) (71) 
0, Anterior papillz absent. 
f, Anterior portion of body covered with 
largespines and often inflated ; remainder 
of body with small spines: in fish 
Deropristis Odh. (Fig. 105) (70) 
f, No large anterior spines. 
g,- CEsophagus long; uterus short; recep- 
taculum seminis and testes large: in 
fish 
Allocreadium Lss. (Fig. 37) (44. 45) 
gy. Œsophagus very short or wanting; 
receptaculum seminis absent or 
small. 
r, Yolk glands extend back of 
testes. 
s, Large suckerlike genital pa- 
pila present in front of 
acetabulum ; uterus extends 
to end of body 
Ptychogonimus Lühe (Fig. 38) (51) 
5, No geni papilla present; 
uterus short, in front of 
testes; prepharynx present; 
in birds and fish 
Psilostomum Lss. (Fig. 39) (44) 
7, Yolk glands do not extend back 
of testes; ovary far from ace- 
tabulum, the space between 
filled by the uterus; body elon- 
gate: in fish 
Azygia Lss. (Fig. 40) (44) 
Ja- Testes either two in number, in same transverse plane in hinder end 
of body, or many in number. 
k. Testes numerous, in median field of body; no pharynx present; 
ovary just back of acetabulum: in ducks 
rip Brn. (9) 
£, Testes two in number, in same semet 
sparen IX Colonin 
4. Genital pore in e ; yolk glands very voluminous : 
in birds . Hoike Lühe (Fig. 41) (50, 10) 
