California Xanthidae — Knudsen 
15 
returned and were picked up in the water. Still 
other cards were caught in an offshore current 
and carried far to the south. 
It is evident that the currents around Palos 
Verdes are irregular and frequently shift direc- 
tion within a short time. Wind, tide level, and 
bottom topography may all serve to create and 
alter these currents. It is also evident that the 
currents observed are peculiar to a narrow strip 
of water embracing the headland, and that the 
California Current has little or no effect here. 
That the California species of Xanthidae are not 
rapidly disappearing from Palos Verdes sug- 
gests this also. The writer believes that a portion 
of xanthid larvae are caught in a southerly cur- 
rent (Experiment 5) and die in the first crab 
stage when a suitable habitat is not found. This 
is suggested by first crabs and megalops clinging 
to drift algae, and by the deep water distribution 
of L. b. diegensis. 
Macro cystis Beds 
Along the major portion of the range of 
the California species of Xanthidae are found 
large beds of the giant brown kelp, Macro cystis 
pyrifera. This alga grows in water from 30 to 
90 feet deep all along the rocky shores. In the 
summer it forms a very thick mat of growth at 
the surface which divides the outer oceanic 
water from a thin strip of water between the 
kelp beds and the shore. A single bed often 
extends for many miles along the coast without 
interruption. 
Such dense, uninterrupted growths could serve 
to ( 1 ) protect larvae, ( 2 ) offer hiding places 
where the cycle could be completed, and (3) 
alter currents to maintain an inshore eddy sys- 
tem. Andrews (1945: 36) concludes that kelp 
beds at Monterey, California, check currents and 
wave action, and offer protection to develop- 
ing larvae. Limbaugh (1955: 13) reports the 
"dumping” of long waves which reach the kelp 
beds, but states that short waves pass through 
them with little interference. 
Of the animal life in the canopy of Macro - 
cystis there are such forms as pelagic and near- 
shore fishes and invertebrates, especially larval 
forms (Limbaugh, 1955: 14). The writers 
plankton net collecting did not indicate plankton 
to be more abundant in kelp beds, but the 
amount of work done is so small (18 net hauls, 
half in kelp beds ) , and accomplished under such 
awkward conditions (small skiff and inner-tube 
raft), that it is of no significance. Limbaugh 
records less plankton collected in the kelp beds 
than such places as over rocky nearshore bottom 
where plankton is abundant. He explains this by 
the abundance of fish which filter feed in the 
kelp beds and thus reduce the plankton there. 
However, difficulty in using a net in kelp beds 
may also explain this difference. The significant 
points demonstrated are ( 1 ) that schools of fish 
are attracted to feed in the kelp beds, denoting 
a concentration of plankton which probably seek 
shelter there, and (2) the presence of a large 
number of larvae inshore from the kelp beds. 
It seems apparent that the kelp beds and/or 
peculiar nearshore currents are holding the larvae 
and thus preventing a reduction of species along 
our coast. 
Inshore Migration 
Unless a mechanism such as that suggested 
above keeps the xanthid larvae close to their 
habitat area, the megalops stage must migrate 
inshore at the time of metamorphosis. The drift 
card Experiment 4 shows that currents are, at 
times, very favorable to inshore migration of the 
larvae. Rafting on drift algae may be a second 
method employed by xanthid crabs to migrate 
inshore. Cunningham (1898: 205), Lebour 
(1928: 499; 1947: 528-535 ), and Hiatt ( 1948: 
204) report finding megalops and/or first crab 
stages along the beach. The writer has also re- 
covered the megalops of Pachygrapsus cras- 
sipes , Hemigrapsus nudus, and Lophopanopeus l. 
leucomanus at the bay, thus suggesting that the 
megalops stage completes metamorphosis after 
reaching the adult habitat. 
Early Crab Stages 
The early crab stages of Paraxanthias taylori, 
Lophopanopeus l. leucomanus, and Cycloxan- 
thops novemdentatus were found on many oc- 
casions along the Palos Verdes shore. These 
resemble the mature adults in carapace propor- 
tions and gross appearance. The young Para- 
xanthias taylori resembles the adult in color also 
while the young of Cycloxanthops novemden- 
tatus and of Lophopanopeus l. leucomanus are 
of many different bright colors. These little 
animals are found in the smallest of cracks or 
