116 University of California Publications in Zoology (Vou. 23 
mark, and downwards to at least three or four fathoms, since large specimens 
were brought up in abundance by the dredging machines in Oakland Harbor. 
Almost every specimen collected in Tomales Bay, in the month of May, bore 
upon its abdominal feet either the curious Isopod Phyllodurus abdominalis [see 
Stimpson, in synonymy above, p. 511] or a small bivalve mollusk, Pythina rugifera 
Carpenter. 
While most of the smaller individuals are accompanied by a pair of P. abdom- 
inalis, the larger specimens were free from this crustacean but in many cases 
bore the mollusk above mentioned. 
In only one case, out of over a hundred specimens dug up in Tomales Bay, 
were the mollusk and the Isopod found in company upon the same Gebia; and in 
this ease the Gebia was of middling size and the mollusk very small. On specimens 
collected July 4, I did not find the bivalve, and the Phyllodurus was less common 
than in May. 
In San Francisco Bay I have not as yet detected Pythina rugifera, but Phyllo- 
durus is sufficiently common. 
Genus Callianassa Leach 
First pair of legs very unequal, with well developed chelae; second pair small 
and chelate; fifth pair subchelate. Eye-stalks triangular or oblong, flattened; 
cornea dorsal, median, small or absent. Rostrum short, triangular, rudimentary, 
or absent. 
KEY TO THE CALIFORNIA SPECIES OF CALLIANASSA 
I. Front with median tooth either obscure or not prominent. Eyes pigmented. 
A. Eye-stalks with acute and divergent extremities. 
1. Median prominence of front rounded; cornea at middle of eye-stalk; 
large cheliped of male very broad, the carpus very little longer 
than wide, but considerably longer than palm, almost twice as 
long. 
californiensis, p. 117. 
2. Median prominence of front subacute; cornea just behind middle of 
eye-stalk; large cheliped of male elongate, carpus from one and 
one-half to twice as long as wide, carpus and palm subequal. 
longimana, p. 117. 
B. Eye-stalks oblong, their inner extremities tuberculiform and not diverg- 
ing; cornea in front of middle of eye-stalk; carpus of large cheliped 
of male very little longer than wide, and very little longer, some- 
times even shorter than palm. (Not known north of Catalina Har- 
bor.) fs 
affinis, p. 119. 
II. Front with a sharp and prominent median tooth. 
A. Eyes not pigmented, eye-stalks oblong; large cheliped of male with 
carpus much shorter than wide. (Known only from 278 + fathoms.) 
goniophthalma, p. 122. 
B. Eyes pigmented, eye-stalks with tips acute and divergent; large cheliped 
of male with carpus a little longer than wide. (Not known south of 
the Gulf of the Farallones). 
gigas, p. 119. 
