No. 417.] WORTH-AMERICAN INVERTEBRATES. 749 
e2. Twelve spines on the dorsal surface of the lorica ; foot 
with two long dorsal spines | 
159, P. subquadratus Perty (Fig. III) 
d2. Two spines on the dorsal surface of the lorica, a very long 
one rising from the middle, a short one from near the posterior 
margin. Head covered with a large semicircular shiel 
160, Stephanops bifurcus Bolton 
43. One spine from the middle of the dorsal surface of the 
lorica ; otherwise much like the last 
161, Stephanops longispinatus Tatem (Fig. 112) 
d4. One long spine from in front of the middle of the dorsal sur- 
face of the lorica ; also four curved spines from the posterior 
margin, and a short median point at the anterior dorsal margin 
162, Brachionus (?) gleasonii Up de Graff (Fig. 113) 
¢3. A broad, nearly circular projecting plate over the head, appear- 
ing like a halo.  Lorica cylindrical or pyriform, covering both 
dorsal and ventral surfaces ; not faceted nor bearing spines on 
the surface (though there may be spines at the posterior edge). 
Foot distinct ; toes two 
dr. Lorica pyriform, with a narrow neck, slightly prolonged 
behind into three subparallel acute spines. Foot with a toe- 
like spine above the two toes 
163, Stephanops lamellaris Ehr. (Fig. 114) 
` 42. Lorica cylindric, with a distinct neck ; dorsal plate prolonged 
eg. 
behind, over the foot, as a spoon-like shield 
164, Stephanops muticus Ehr. 
The very short foot ending in one, two, or more very slender, 
stiff, bristle-like toes; where more than one are present, these 
may be equal or unequal. Lorica cylindrical, fusiform, ovate, or 
conical, closed all around but open at each end, smooth, rather 
thin; frequently showing a tendency to be spirally curved or 
otherwise unsymmetrical in form ; often with one or two longi- 
tudinal ridges. Jaws unsymmetrical. One eye 
Family RATTULID/E 
(The Rattulide are so badly in need of revision that it is difficult to 
give a usable key to the species. Moreover, it is certain that many 
Species in addition to those hitherto recorded will be found in 
America.) 
dı. One long, straight, bristle-like toe (if others are present, 
these are much shorter than the largest one) . Mastigocerca 
er. Lorica with a single marked ridge, passing from the mid- 
dorsal line of the lorica forward and to the right. No teeth 
or spines at the anterior margin of the lorica. A single long 
toe, with three or more minute * substyles ” at its base 
