746 THE AMERICAN NATURALIST. [Vor. XXXV. 
cr. Foot ending in a ciliated cup ; lorica dorso-ventrally flattened, 
thin; corona transverse, ciliary wreath two lateral semicircles ; 
eyes two. . Pterodina 
dr. Lorica very flat, pito, Mig. thin Per without teeth or 
projections . . 138, P. patina Ebr: (Fig. 101) 
(P. valvata is ihe: young g^ 138) 
d2. Lorica oval in dorsal view, concave on the dorsal side ; 
edges of the lorica very thick ; no teeth or other projections 
139, P. reflexa Gosse (Fig. 102) 
d3. Lorica thin, broadly ovoid or nearly circular, with a prom- 
inent tooth on each side at the posterior lateral margi 
140, P. bidentata Ternetz 
c2. Foot ending in two toes (usually small). Lote arched dorsally, 
flat or slightly convex ventrally. Spines or teeth usually (not 
always) present at the anterior dorsal Pu of the lorica (fre- 
quently elsewhere also) . . . Brachionus 
dI. Lorica with szx teeth or spines at he’ anterior margin of the 
dorsal plate (with or without posterior spines) 
ez. The two middle anterior spines longest and curving out- 
ward; ventro-posterior part of lorica slightly prolonged to 
form a sort of sheath for the foot ; on the dorsal side of 
sheath a subsquare piece cut out, so that in dorsal view 
oot orifice appears to be bounded by two or three 
Ed Two posterior lateral spines long, short, or absent. 
(Excessively variable) . . 141, B. ġakeri Ehr. (Fig. 103) 
ft. Posterior spines short B. bakeri, var. brevispinus Ehr. 
fe. Sheath for foot unsymmetrical (right side less developed) ; 
body covered with tubercles 
B. bakeri, var. tuberculus Turner 
e2. Two middle anterior spines longest and curving outward ; 
a square plate projecting from the middle of the posterior 
edge over the foot orifice. Usually two posterior lateral 
spines on the lorica, these disappearing with age 
42, B. variabilis Hempel 
£3. Anterior spines straight; a deep sinus between the two 
median ones. No posterior spines — 143, B. wrceolaris Ehr. 
(fr. Reddish, spines Ary 
rubens, a variation of B. urceolaris) 
d2. Lorica with but four en or spines at the anterior dorsal 
margin 
er. Median anterior spines very short ; lateral ones very long. 
Toes large, each ending in two minute points, so that the foot 
at first view,appears to be bifurcated 
fr. Two posterior lateral spines on the lorica, the left one 
very small, the right one lon 
144, B. (or Schizocerca) diversicornis Daday 
