286 University of California Publications in Zoology [Vol. 23 



Summarized, the foregoing gives : 



Species peculiar to California 41 (23%) 



Species which on the west coast of North America are confined to 



California waters 42 (23%) 



Species found in California and the region north of it 101 (55%) 



Species found in California and the region south of it 95 (52%) 



Species common to California and the regions both north and south 27 (15%) 

 Species finding the northern limit of their range in the Bering Sea 9 ( 5%) 

 Species finding the northern limit of their range in the Aleutian- 

 Southeastern Alaska stretch 47 (27%) 



Species finding the northern limit of their range in the British 



Columbia-Oregon stretch 40 (22%) 



Species finding the southern limit of their range in the Coronados- 



Magdalena Bay stretch 41 (23%) 



Species finding the southern limit of their range in the Gulf of 



California or beyond 39 (21%) 



Species found at Panama or farther south 12 ( 7%) 



Species occurring only in the stretch between the Aleutian Islands 



and Magdalena Bay 133 (73%) 



Species also reported from the western north Pacific, chiefly from 



Japan 17 ( 9%) 



Species also reported from the eastern littoral Atlantic 4 ( 2%) 



Cosmopolitan species 4 ( 2%) 



Pelagic species 2 ( 1%) 



Species having a bathymetric range exceeding 500 fathoms 5 ( 3%) 



The California littoral decapod fauna is almost wholly confined 

 to the west coast of North America; in fact, forty-one (23%) of the 

 forms represented in it are peculiar to California waters alone. 

 Exclusive of cosmopolitan and near cosmopolitan species only sixteen 

 (9%) have been reported from the western North Pacific, chiefly 

 from Japan, and only twelve (7%) from as far south as Panama or 

 farther. If we consider Crangon dentipes, which occurs also in the 

 Mediterranean and the Cape Verde Islands, as near cosmopolitan, 

 only one non-cosmopolitan California species is common to the Atlan- 

 tic littoral, viz., Epialtus bituberculatus. 



That nearly three-fourths (73%) of the species systematically 

 treated in this paper, range, on the west coast of America, only within 

 the stretch lying between the Aleutian Islands and Magdalena Bay 

 seems indicative of the existence of a more or less uniform and con- 

 tinuous faunal area of like extent, 2 within which these species are so 



2 North of California there are (based on Rathbun, 1904a, pp. 6, 7, and accom- 

 panying table) but seventy-seven species occurring within the 100 fathom line 

 which have not been reported from California. Of these twenty (26%) do not 

 range north of the Aleutians, being confined to the stretch lying between those 

 islands and the coast of Oregon; fifty-seven (74%), however, find their northern 

 limits either in the waters of Arctic Alaska or the Bering Sea. But of the latter 



