174 University of California Publications in Zoology [Vou. 23 
Dimensions.—Length of carapace 29 mm., width 23 mm., length of telson 
19 mm., width of telson 9.5 mm., length of abdomen when extended 37 mm. The 
ratio of the length of the carapace to its width is quite variable (Holmes). The 
length of the carapace of the Biological Survey specimens ranged from 10 to 25 
mm., averaging about 17 mm. 
Color—A bluish or cinereous color above and yellowish white below; the 
fringing hairs are mostly black (Stimpson). 
Type Locality.—California. 
Distribution.—According to Holmes this species extends from Oregon to 
Panama. The collections in the U. S. National Museum range from Drake’s Bay, 
California, to San Bartolomé Bay, Lower California, and from Peru to Chile. 
The intermediate region (from Lower California to Panama) is represented by 
E. emerita (Fabricius), which occurs also on the Atlantic side of tropical America 
(Rathbun). 
Remarks.—The sand crab inhabits a strip of beach in or near the wash of the 
waves. Here it is distributed from the high-tide limit, for a given tide, to a short 
distance beyond the point where the waves strike the sand, but the center of 
abundance is that portion washed by each wave.... 
Although occasionally found singly, Hmerita is essentially a gregarious animal. 
It occurs in large ‘‘beds,’’ which are marked by small \-shaped ripples in the 
sand. Here, as Leidy has said of the eastern form, they are as thick as currants 
in plum pudding. If one turns over the sand of one of these beds he will find 
the sand crab in incredible numbers lying within a few inches of the surface. In 
these places adults and young of both sexes may be found associated. Generally 
mature females and males are at once distinguished by the difference in size.... 
For this reason collections often consist of females only, the smaller males being 
regarded as young. Measurements of the carapace of 27 specimens (length from 
rostrum to median posterior dorsal margin) of each sex collected at Pacific Grove 
give the following: average of males (all with enlarged genital papillae) 12.4 mm., 
range 10.5 to 14.5 mm.; average of females (all egg-bearing) 21.4 mm., range 
17 to 25.55 mm. The males are without pleopods, while the second, third and 
fourth segments of the abdomen of the females are provided with them. The 
telson of the adult female is more heavily ciliated along its lateral margin and is 
somewhat wider than that of the male. The following are measurements of two 
typical specimens: female, length of carapace 20.3 mm., length of telson 13 mm., 
width of telson 6.9 mm., width 53% of length; male, length of carapace 11 mm., 
length of telson 7.6 mm., width of telson 3.3 mm., width 43% of length. (Wey- 
mouth and Richardson.) 
Biological Survey of San Francisco Bay—There are only three 
specimens of Emerita analoga in the bay collection: one, which was 
apparently alone, was dug up in the sand on the beach skirting the 
Presidio shore west of Fort Point; another was obtained while seining 
on the Fort Baker beach, and the third was taken, also in the seine, 
on the beach west of Blunt Point, on the southern shore of Angel 
Island. Owing to lack of more intensive sandy beach collecting no 
definite statements can be made regarding the distribution and oceur- 
rence of this species in the region covered by the survey. 
Family PorcELLANIDAE 
Body crab-like. Abdomen bent under and folded against the thorax; tail-fan 
well developed. First pair of legs chelate, moderately elongate, stout; fifth pair 
small and elevated so that they rest on the carapace. 
