No.4175.] MWORTH-AMERICAN INVERTEBRATES. 753 
e2. No spine between the two toes . 192, D. Zetractis Ehr. 
d2. Lorica somewhat vase-shaped, thin, smooth, and transparent ; 
head with a thin chitinous covering ; eye very close to or upon 
De mastar oo 22000. Ved See pl ee ae 
ez. Body nearly cylindrical or slightly compressed laterally ; 
body, foot, and toes of about equal length 
193, S. longicaudatum Ehr. (Fig. 135) 
22. Body broad, ovate or pear-shaped ; toes about as long as 
body and foot together 194, S. eudactylotum Gosse (Fig. 136) 
c7. Lorica of two dissimilar plates, one dorsal and one ventral, the 
former usually larger and arched (except in No. 201), the latter 
flat or slightly convex. Large transparent rotifers, with a single 
eye. Foot jointed, the two toes large, usually blade-s aped 
Euchlanis 
di. Lorica oval or ovate, gently arched above, nearly flat below ; 
transverse section a low segment of a circle 
ez. Ventral plate with a flange projecting laterally from its 
junction with the body; anterior dorsal edge with a broad 
gap having a straight bottom (Fig. 138); hind dorsal edge 
notched. . . . . . . 195, E. dilatata Ebr. (Fig. 137) 
e2. Ventral plate without a lateral flange; anterior dorsal 
margin with a small subsquare notch | 196, Æ. deflexa Gosse 
42. Lorica a long, narrow oval or an ellipse, depressed ; anterior 
dorsal edge membranous ; transverse section a low circular 
segment ; ventral plate elliptical and broadest at the hind end 
197, EK. lyra Hudson 
43. ‘Lorica broadly oval or ovoid, constricted near the middle, 
the dorsal plate much wider than the ventral and turned 
downward and inward . 108, Æ. pyriformis Gosse (Fig. 139) 
d4. Lorica roof-shaped, with sloping sides ; not rising to a ridge; 
cleft for a short distance behind. Ventral plate flat, smaller in 
outline than the dorsal. A small species, 199, Æ. oropha Gosse 
d5. Lorica with a high median dorsal keel; lateral edges of the 
lorica extending laterally into two wide shelves, so that the 
animal seems to have three keels, and is triangular in section. 
Outline from above ovoid . . . . 200, E. triquetra Ehr. 
dó. Dorsal plate carinate ; lorica ovate, flask-shaped ; foot four- 
jointed ; toes more than half the length of the lorica 
201, E. ampuliformis Herrick (E. propatula) Gosse (?) (Fig. 140) 
£8. Lorica of two plates, the ventral one nearly flat, the dorsal one 
slightly or considerably elevated. The two plates separated by a 
deep lateral furrow covered with flexible membrane. Body ending 
posteriorly in either one or two large rod-shaped toes (the foot 
Proper being short and inconspicuous). One eye 
Family CATHYPNADE 
