422 
PACIFIC SCIENCE, Vol. XIV, October I960 
havior of males with males and with the cast 
skin of a female. It is tempting to compare this 
crab pattern to the now classical picture of the 
stimulus-reaction chain of the three-spined 
stickleback (Tinbergen, 1951). 
The complexity of the sexual behavior of P. 
crassipes seems to have no parallel among the 
Crustacea with the exception of the genus Uca, 
where Crane (1941) found species differences 
in sexual posturing and a complex and variable 
pattern of courtship. The behavior cited in the 
present report may be equally variable under 
natural conditions. The singularity of such com- 
plex behavior patterns in crustaceans may be 
more apparent than real when the amount of 
investigation devoted to them is considered 
relative to that given to insects and vertebrates. 
ACKNOWLEDGMENTS 
These observations were made at the Hopkins 
Marine Station of Stanford University while I 
was there as Acting Associate Professor of Biol- 
ogy in Marine Ecology during the summer of 
1958. I wish to take this opportunity to express 
my gratitude to the entire staff of the station, 
and to its director, L. R. Blinks, for their en- 
couragement and stimulating company. 
REFERENCES 
Andrews, E. A. 1895- Conjugation in an Amer- 
ican crayfish. Amer. Nat. 29: 867-873. 
Bovbjerg, R. V. 1956. Some factors affecting 
aggressive behavior in crayfish. Physiol. Zool. 
29:127-136. 
Chidester, F. E. 1911. The mating habits of 
four species of the Brachyura. Biol. Bull. 21: 
235-248. 
Crane, J. 1941. Crabs of the genus Uca from 
the West Coast of Central America. Zoologica 
26: 145-208. 
Hiatt, R. W. 1948. The biology of the lined 
shore crab, Pachygrapsus crassipes Randall. 
Pacif. Sci. 2(3): 135-213. 
Tinbergen, N. 1951. The Study of Instinct. 
Oxford. 
