1921 ] Schmitt: The Marine Decapod Crustacea of California 301 



V. POSTSCRIPT 



It is of more than passing interest to be able to notice, and compare 

 here, the rather close correspondence between the conclusions set forth 

 immediately above regarding the local distribution of the decapods 

 of the Survey, and those independently arrived at by Packard (1918a, 

 1918&) as a result of his studies of the "Molluscan Fauna from San 

 Francisco Bay," and published after the present paper had gone to 

 press, viz : 



"The character of the bottom appears to have the greatest sig- 

 nificance in determining the local distribution of the mollusca" 

 (1918&, p. 245). "Depth has little significance in determining the 

 distribution of local forms . . . the significance of the temperature 

 factor is obscure" (1918a, p. 331). "The salinity factor is considered 

 to be the major one in accounting for the meagerness of the fauna of 

 the upper in contrast to that of the other divisions of the bay" (1918&, 

 p. 245). 



Recently in The factors controlling the distribution of the Poly- 

 noidae of the Pacific coast of North America, Miss Essenberg (1918) 

 has adduced what appears to be further evidence in favor of Point 

 Conception as a faunal barrier, marking a dividing line between a 

 north temperate zone (extending north to Cape Flattery) and a north 

 subtropical zone (extending south to Cape San Lucas). 



But if we treat the species listed by Miss Essenberg in the same 

 manner that the California decapods were dealt with under their 

 Geographical Distribution above (pp. 281 to 286), we find of the 

 twenty-eight species of littoral record (from 100 fathoms or less) 

 from off California, that seven (25%), so far as known at present, 

 are restricted to the region north of Point Conception, and nine 

 (32%) to the region south of it, while twelve (43%) range both north 

 and south. 



Of these twenty-eight polynoids of littoral record, the bathymetric 

 range of twelve (43%) reaches beyond the 100-fathom line. It does 

 not, therefore, seem unreasonable to expect that with more intensive 

 collecting and dredging a considerable number of species at present 

 only found south, will, be found north of Point Conception as well, 

 and vice versa, especially in view of Miss Essenberg 's warning that, 

 "the distribution of some of the species is as yet inadequately known" 

 (1918, p. 175). 



