1921 ] Schmitt: The Marine Decapod Crustacea of California 287 



distributed as to preclude subdivision into smaller regions or -districts 

 (cf. appendix I, p. 310). 



Arguing from the distribution of the hydroids of the west coast 

 of North America, Dr. C. McLean Fraser asserts (1911, p. 6) that, 

 "The more the group is studied and the greater the number of loca- 

 tions for examination included, the more reason there is for believing 

 that there are no sudden, nor comparatively sudden breaks in dis- 

 tribution along the entire West Coast, though naturally certain species 

 disappear and others as gradually come in." 



In an earlier paper on the same group of organisms (hydroids) 

 Dr. Torrey noticed (1902, pp. 6, 7) that "from Alaska Peninsula to 

 San Diego there are no abrupt transitions in the fauna." Although 

 thinking "it possible, for purposes of comparison, to divide this great 

 region into four subregions, " viz., (1) Alaska Peninsula to Sitka, 

 (2) Puget Sound, Vancouver Island and vicinity, (3) San Francisco 

 Bay and vicinity, including Monterey Bay, (4) Southern California, 

 south of Point Conception, he expressed the feeling, later justified 

 by Dr. Fraser, that, "future exploration will doubtless reduce these 

 differences. ' ' 



In a recent monograph on the shallow water starfishes of the north 

 Pacific coast from the Arctic Ocean to California, Professor A. E. 



very few are to be found south of the Aleutians in less than 100 fathoms; only 

 seven range as far south as Puget Sound, although some ' ' are often found out of 

 their normal region in the cold glacier-fed bays and sounds of southeastern 

 Alaska. ' ' 



Unalaska is probably the western limit of the faunal region suggested, as 

 approximately 20% of the northwardly ranging California and 40% of the "north 

 of California" decapods occurring in the Aleutian-Oregon stretch, find there their 

 northern limit. 



South of California comparatively little is known of the Lower Californian 

 and Gulf of California faunae other than what has been listed in this paper, or 

 in Miss Eathbun's "Descriptions of New Genera and Species of Crabs from the 

 West Coast of North America" (1893) ; "Brachyura of the 'Albatross' Voyage, 

 1887-1888" (1898), and "Stalk-eyed Crustacea of Peru" (1910). An approxi- 

 mate tabulation of Miss Eathbun 's lists gives a total of one hundred and twenty- 

 four species from the Gulf of California and the west coast of Lower California. 

 Irrespective of their southern ranges, forty-three species are not found north of 

 the Gulf; thirty are reported from Cape St. Lucas; and twenty-five reach Magda- 

 lena Bay; only fifteen go beyond, of which only four are found north of Abreojos 

 Point, two at San Bartolome (or Turtle) Bay, and two off Cerros Island. The 

 eleven unaccounted for bear the indefinite locality label "Lower California." 

 Miss Eathbun, in her Peruvian lists, so designated twenty-six; species, but refer- 

 ence to original sources reduced that number to eleven. 



The papers of Faxon (1895) and Bouvier (1895a and 1898) were consulted, 

 but barring species already cited practically none of Faxon's come within the 

 100 fathom limit, while Bouvier described about fifteen new species, all of which 

 seem to be confined to the Gulf of California. 



The fauna of the Gulf of California is largely peculiar to it alone, and is 

 more related to that of the Panama region than to any further north. 



