752 THE AMERICAN NATURALIST. [Vor. XXXV. 
ez. Spines or teeth on the lorica as follows: two anterior 
dorsal two anterior ventral, one (median) posterior dorsal, 
two posterior ventral. (Spines all rather short, tooth-like) 
. 183, .S. mucronata Ehr. (Fig. 131) 
e2. Spines or teeth as follows : no anterior dorsals, two anterior 
ventral one posterior dorsal, two posterior ventral. (The 
four following species are distinguished, all having the above 
characters ; it is possible that they should be considered 
mere variations of a single species, S. ventralis Ehr.) 
fr. Anterior ventral spines short and straight ; posterior 
spines all short, the ventral ones recurved 
184, S. brevispina Ehr. 
fe. Anterior ventral spines very short, posterior dorsal spine 
short, decurved ; posterior ventral pair longer than the 
posterior dorsal ; lorica with a stippled collar 
185, S. ventralis Ehr. 
f$. Anterior ventral spines short, straight ; posterior spines 
all long and straight, the ventral ones much the longer ; 
lorica surface not stippled ; dorsal cleft wide 
186, .S. macracantha Gosse 
f4. Anterior ventral spines short, incurved ; posterior dor- 
sal conical, short, arched ; posterior ventral long, stout, 
incurved ; dorsal cleft narrow ; lorica frequently stippled 
187, .S. eustala Gosse (Fig. 132) 
. No posterior spines; anterior dorsal pair very long ; 
anterior ventral pair also long and slender, but only about 
half as long as the dorsal ones. Lorica broad 
188, S. macrocera Jennings (Fig. 133) 
d3. Lorica as in d2, but without spines ; the eye lacking —— 
Diplax 
er. Body triangular in section ; lateral outline of lorica nearly 
ovate, but strongly arched dorsally and nearly flat ventrally 
189, D. trigona Gosse 
£2. Body much compressed, long and narrow in dorsal view, in 
side view nearly a parallelogram . 190, D. compressa Gosse 
có. Foot very long, of several joints; the two toes very long ; 
lorica entire (not cleft dorsally nor ventrally), vase-shaped Ot core 
pressed, not bearing spines. Head furnished with a chitinous 
covering. Eye one : 
dr. Lorica vase-shaped, faceted, and with surface roughened ; 
head retractile within a chitinous cap; eye one; foot bearing 
two spines dorsally ; foot and toes together nearly or quie 
twice the length of the body. . . . + +: : Dinocharis 
ez. A short spine dorsally between the two toes 
191, D. focillum Ehr. (Fig 134) 
