316 
PACIFIC SCIENCE, VoL XVII, July 1963 
corniculata hoppers may occur at the ends of the 
beach where conditions are not optimal for 
calif ornicma. I have never found calif orniana on 
corniculata-&omimx£<\. beaches. 
For columbiana and pugettensis I have not 
gathered enough data to make very meaningful 
statements here. They often occur together on 
coarse sand beaches, some of which are quite 
long, onto which relatively little seaweed is cast 
as food for the hoppers. 0 . benedicti is com- 
monly found with calif orniana, and otherwise 
lives on beaches of the finest, silty sand. 
It is not always easy to find mature individuals 
in the daylight on a beach and much sample 
digging is often required to locate a ''bed” of 
hoppers. Small individuals are readily found but 
are not so readily captured. The distribution of 
hoppers on a beach is not of a random nature, 
but is dictated by the location of seaweed, the 
main food of these omnivores, on the shore, and 
by the tidal cycles, which they tend to follow up 
and down the beach. Since these animals feed 
mostly at night on the freshest drift present and 
many remain under this drift at dawn, the most 
productive searching is usually done under the 
seaweeds brought ashore by a high tide of the 
previous night. Large individuals, however, may 
move farther up the beach; and in calif orniana, 
at least, the mature males and some females in 
the breeding season (probably February to 
October) with eggs or young in their brood 
pouches will be found scattered in fairly high 
and dry zones that may not have been reached 
by the surf for some days. 
The location of the burrows of these large 
animals requires careful observation in the early 
daylight hours. In digging the burrow, or clean- 
ing out an old one, large calif orniana kick sand 
out onto the surface in two opposite elongated 
rays. If this sand is of a different color because 
of a higher moisture content or because it was 
obtained from different-colored material below, 
it may be quite noticeable. However, during 
the day, drying action of the wind and sun may 
reduce the color difference between the burrow 
sand and the surface sand, and the winds level 
the elongated heaps, making them increasingly 
difficult to see. The burrows may be open shafts 
up to 12 inches in depth, with a plug of sand 
in the mouth of the burrow. 
O. corniculata make burrow mounds much 
more like those of a pocket gopher. The sand is 
Fig. 1. Sketch of O. calif orniana to show features mentioned in the text. 
