16 
PACIFIC SCIENCE, Vol. XIV, January I960 
spaces between snail tubes, or even, in the case 
of Lophopanopeus l. leucomanus, in the dense 
coralline turf on top of rocks in the xanthid 
habitat. Edcysis is probably carried out in the 
security of such places. The early crab stages 
molt every 10 to 15 days and grow rapidly in 
their first year. The smallest crab stages feed on 
microscopic red algae which grow in the shaded 
areas of their habitat. The small crabs are easily 
attracted to raw meat, such as abalone, but it is 
doubtful if their diet contains much of this. The 
megalops and first crab stages have many en- 
emies in blennioid fishes and other crabs. While 
making periodic underwater observations, it was 
noted that blennioid fish occupy the xanthid 
habitat at high tide. These fish spend much of 
their time lying in wait on top of algal covered 
rocks. At times they were seen to dart away from 
their hiding place to catch isopods. When small 
xanthid crabs were dropped nearby the fish 
made a serious effort to capture them. This sug- 
gests that the blennioid fish may be preying 
upon the xanthid crabs. To test this suggestion, 
stomach examinations were made on 51 blen- 
nioid fishes of the following species: 31 Clino- 
cottus analis (Girard), 5 Olygocottus maculosus 
( Girard ) , 3 Artedius lateralis ( Girard ) , 5 Gib- 
bonsia eligans (Cooper) , and 7 Gibbonsia metzi 
Hubbs. The stomachs contained many limpets, 
snails, polychaetes, crustaceans, and small fishes. 
Of the Crustacea there were isopods, amphipods, 
Caprelia, stomatopods, shrimp, porcellanids, her- 
mit crabs, and the following Brachyura: Pachy- 
grapsus crassipes, Lophopanopeus spp., Pugettia 
producta, and Herbstia sp. In the stomach con- 
tents crustaceans were dominant, while mollusks 
were second in volume. Both adults and mega- 
lops of the genus Lophopanopeus were found, 
thus establishing the blennioid fish as enemies 
of the Xanthidae. 
SUMMARY 
1. Sexual dimorphism of the California Xan- 
thidae is manifested in the abdomen of mature 
and submature specimens. 
2. The immature, submature, and mature 
specimens of Cycloxanthops novemdentatus, 
Lophopanopeus l. leucomanus , L. bellus diegen- 
sis, and Paraxanthias taylori may be separated 
by noting the width of the abdominal segments, 
the length of the lateral abdominal hair, the 
presence or absence of the abdominal lock, and 
the condition of the pleopods. 
3. The internal and external genitalia are 
similar in all species of the California Xanthidae 
and are described for both sexes. 
4. Xanthid crabs breed in a hard shell condi- 
tion. The male is always above the female, trans- 
ferring sperm to her vulvae by means of the 
intromittent organs. 
5. Lophopanopeus spp. begin breeding earlier 
in the season and have more broods per season 
than the other genera. Cycloxanthops novem- 
dentatus has the shortest breeding season. 
6. Eggs vary in number, with the species and 
with the size of the individual, from 1,000 to 
45,000. They are attached to the pleopods and 
there aerated and cleaned by the female until 
hatching. 
7. Hatching occurs generally at night. There 
is no molt between the prezoeal and first zoeal 
stages. There are four zoeal and a single mega- 
lops stage in the xanthid life cycle (which re- 
quires about five weeks to complete ) . 
8. The xanthid zoeae are photopositive and 
swim by means of the maxillipeds or with maxil- 
lipeds and telson. The megalops use their pleo- 
pods for locomotion. 
9. Zooplankton probably constitutes the lar- 
val food in nature. Zoeal feeding methods are 
described herein. 
10. The process of molting of the zoeae and 
megalops is essentially the same as in the adult. 
11. Data collected suggest that peculiar eddy 
currents exist in bays and coves along the Cali- 
fornia coast which hold the developing larvae 
close to shore and prevents their removal by the 
southerly California Current. 
12. Macro cystis beds help isolate developing 
larvae, offer wave protection and perhaps hiding 
places as well. 
13. Megalops of the Xanthidae probably 
metamorphose in the adult habitat since the first 
crab stages were found there in abundance. 
REFERENCES 
Broekhuysen, G. J. 1936. On development, 
growth and distribution of Carcinides maenas 
(Linne). Arch. Neerl. de Zool. 2(2): 257— 
399, figs. 1-8, tables 1-31. 
