No. 417.] MORTH-AMERICAN INVERTEBRATES. 735 
d2. Eyes in the “neck D 2 over the brain, jt above 
the jaws . . Philodina 
ez. Three mts in Hiec jaw (Fig. $e» 
fT. Body beset with strong spines on the dorsal surface 
47, P. aculeata Ehr. (Fig. 34) 
f2. Body without spines, surface usually sticky, so that it is 
frequently covered with débris ; spurs long and sharp, two 
and one-half times as long as the width of the joint to 
which they are attached . . . 48, P. macrostyla Ehr. 
22. Two teeth in each jaw 
Jt. Body smooth, colorless, very short, thickened in the 
middle; corona very large ; foot sharply set off from the 
body ; spurs shorter than the width of the joint to which 
they are attached  . 49, P. megalotrocha (Fig. 35) 
J2. Body colorless or reddish, not short and thick ; foot not 
distinctly marked off . . 50, P. roseola Ehr. 
J3. Body greenish yellow, othé wis much like the last 
51, P. citrina Ehr. 
EK Eyes none: 2 55. s 0E Cm . . Callidina 
(The genus Callidina is a very large and difficult one; while the following 
species are all that have been identified in America, doubtless many more will be 
er. Living ina tube . . . 52, C. eremita Bryce (Fig. 36) 
e2. Not living in a tube ; 
J?. Body with stout, blunt dorsal papillæ, especially on the 
segment next to the foot 
53, C. papillosa Thompson (Fig. 37) 
J2. Body without papillæ or spines 
gf. Foot ending in toes 
hi. Jaws (Fig. 38) small, with numerous (8-10) fine 
ridges (“ teeth ”) 
i1. Corona as wide as the neck ; ridges (“teeth ”), 
ten in each jaw (Fig. 38) ; spurs drawn to a slender 
point c. . 54, C. elegans Ehr. (Fig. 38) 
72. Corona not so vie as the neck ; ridges or teeth, 
eight in each jaw (Fig. 39) ; spurs (Fig. 40) short 
and broad 
55, C. constricta Dujardin (Figs. 39 and 40) 
A2. Jaws with but two distinct teeth (in addition to a 
number of fine ridges) 
tz. Teeth two in each jaw; spurs at least twice as 
long as the width of the joint to which they are 
attached, straight and thick ; body colorless. Para- 
sitic on Asellus 56, C. socialis Kellicott (Fig. 41) 
