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University of California Publications in Zoology VoL. 23 
III. SYSTEMATIC DISCUSSION OF THE CALIFORNIA 
REPRESENTATIVES OF THE ORDER DECAPODA 
Key TO THE SUBORDERS OF THE DECAPODA 
I. Body almost always laterally compressed (macrurous, shrimp-like). First 
abdominal segment not much smaller than the rest. First antennae usually 
having a scale at base; second antennae with scale generally large and 
lamellar. Legs usually slender except sometimes a stout chelate limb or 
pair, which may be any one of the first three pairs, with basipodite and 
ischiopodite never coalesced, and only one fixed point in the carpo-propodal 
articulation. Male genital apertures in the articular membrane between the 
coxopodites of the last (fifth) pair of legs, and the body; female genital 
apertures on the coxopodites of the third pair of legs, (except in one genus, 
Leucifer, not represented in California fauna; the sex of ovigerous females 
is self-evident). Pleopods always present in full number, well developed, 
and used for swimming. 
Natantia, p. 18. 
II. Body not well compressed, usually depressed (anomurous, hermit-crab-like, or 
brachyurous, crab-like, rarely macrurous, shrimp-like). First abdominal 
segment distinctly smaller than the rest. First antennae without a scale; 
second antennae, scale generally small or absent. Legs strong, first pair 
usually stouter than their fellows, others never so, basipodite and ischio- 
podite almost always coalesced in the first pair and generally in the others; 
two fixed points in the carpo-propodal articulation. Male genital apertures 
on the coxopodites of the last (fifth) pair of legs or on the sternum of the 
corresponding somite; female genital apertures on the coxopodites of the 
third pair of legs or on the sternum of the corresponding somite (the sex 
of ovigerous females is self-evident). Pleopods often reduced or absent, 
rarely used for swimming. 
Reptantia, p. 104. 
SUBORDER NATANTIA 
Kry TO THE TRIBES OF THE NATANTIA 
I. Pleura of second abdominal segment overlap those of first; abdomen generally 
with sharp bend. Third legs not chelate. 
Carides, p. 26. 
II. Pleura of first abdominal segment not overlapped by those of second; abdomen 
without sharp bend. Third legs chelate. 
A. Legs of third pair not stouter than those of first two pairs. 
Peneides, p. 19. 
B. One or both legs of third pair longer and much stouter than those of first 
two pairs. (No representatives of this group found in the region cov- 
ered by this paper.) 
Stenopides. 
