38 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 125 
it has become adapted apparently to the lower salinities, higher tem- 
peratures, greater turbidity, currents, and wider fluctuations in en- 
vironmental factors prevailing in the bay as compared to the open 
seacoast. 
The southern Pacific group is poorly defined in this survey. Although 
six species were taken only from buoys along the southern California 
coast, only one has never been reported north of Pomt Conception, 
namely, Paracerceis sculpta. Of the remaining five species, three are 
known from both southern and central California (Jaeropsis dubia, J. 
d. paucispinis, and Janiralata rajata) ; one has been found in southern 
and central California and British Columbia (Anatanais norman) ; and 
one is known to be distributed along the entire Pacific coast from 
southern California to Alaska (Idotea resecata). The latter two species 
actually should not be assigned either to the southern or to the north- 
ern Pacific group. It should again be emphasized that the buoy collec- 
tions do not sample adequately the long Pacific coast or even the 
included section between San Diego and Puget Sound and that knowl- 
edge of the systematics and distribution of isopods and tanaidaceans 
of the Pacific is incomplete. 
As indicated above, the latitudinal zonation on both coasts is de- 
finite for two isopod families, the Idoteidae and Sphaeromatidae. All 
eight idoteids in the collection were found on northern buoys, generally 
associated with kelp, whereas all but one of the eight sphaeromatids 
were taken from warm water buoys, usually associated with muddy 
or sandy bottoms often with soft fouling (tunicates, etc.). Several 
exceptions may be noted in both families. As previously mentioned, 
idotea resecata ranges from Los Coronados Islands (off San Diego, 
Calif.) to Alaska, and in the present survey it was collected on buoys 
as far south as Santa Barbara. Two other idoteids (Synidotea harfordi 
and S. magnifica) are known only from southern California (they were 
not taken in the buoy survey). Conversely, two sphaeromatids in the 
buoy collection from cold waters are Gnorimosphaeroma oregonensis, a 
common species along the entire Pacific coast north of Pomt Concep- 
tion but absent in southern California, and Sphaeroma quadridentatum, 
which ranges both north and south of Cape Hatteras on the Atlantic 
coast. Many other sphaeromatids (not taken in the collection) also 
occur in northern waters; nevertheless, as a rule, idoteids (and other 
valviferans) generally are found in cold waters and sphaeromatids in 
warm waters. 
Not only are idoteids poorly represented in tropical-subtropical 
regions, but also those found there are relatively small (e.g., Colidotea 
edmondsont of Hawaii) compared to more northern species. Indeed, 
valviferans seem to follow Bergmann’s rule (for homoiotherms) as 
they tend to increase in size poleward with some frigid zone species 
