January 10, 1902.] 



SCIENCE. 



63 



Bryozoa of the regions worked in during 

 the summer is the great abundance of the 

 Endoproct Ascopodai-ia macropes. At no 

 other point on our shores have we foimd 

 this or any other Endoproct very plentiful. 

 At San Pedro, however, nearly every rock 

 one turns over presents a continuous mov- 

 ing field of this or a closely related species. 



Mollusca. — No group of marine inverte- 

 brates of the Pacific coast of North Amer- 

 ica has been so extensively studied, syste- 

 matically, as the shell-bearing mollusca. 

 For this reason, then, if for no other, these 

 animals are of special importance for 

 studies on geographic and bathymetric dis- 

 tribution. 



The expedition was fortunate in having 

 for nearly the entire summer two such en- 

 thusiastic and well-informed eonehologists 

 as Professor Raymond and Mrs. Oldroyd 

 in its membership ; and a vast amount of 

 material was secured, the detailed examin- 

 ation of which is, of course, still far from 

 complete. Some idea of the wealth of the 

 collections in the group may be gained 

 from the statement that in the San Pedro 

 and Santa Catalina Island areas alone two 

 hundred and thirty species, exclusive of 

 the Polyplacophora and Pteropoda, have 

 been identified, and it is certain that the 

 number Avill be largely increased by more 

 detailed study. A few species are almost 

 certainly new to science, though just how 

 many it is not yet possible to say. 



The total number of species of mollusca 

 of the Pacific coast of Canada contained in 

 the list published by Rev. G. W. Taylor in 

 1897 is two hundred and seventy-nine. 

 The total number in the list of species of 

 Los Angeles County, now in course of 

 preparation and nearly complete, by Mrs. 

 Oldroyd, is something over five hundred. 



The familiar, though nevertheless strik- 

 ing, general rule of the occurrence in com- 

 paratively deep water off shore of species 

 that are strictly littoral to the northward, 



receives many illustrations in this group. 

 A good example is furnished by Priene 

 oregonensis Redfield, which occurs in a 

 few fathoms at Sitka, Alaska, and was taken 

 this summer in about one hundred fathoms 

 off San Diego. Cryptochiton stelleri, also 

 found in this locality for the first time this 

 year, I believe, is another example of the 

 same sort. 



Professor Raymond has elsewhere* ex- 

 pressed the view that Point Conception 

 marks a dividing line between moUuscan 

 f aunte to the north and south of it that are 

 quite distinct ; and Dallf affirms that Point 

 Conception is the northern limit of the 

 Panamic fauna. 



The results of the summer's work, so far 

 as they can yet be seen, confirm these 

 views. To harmonize the apparent fact of 

 this f aunal delimitation with the view that 

 the Davidson inshore current flows out of 

 the Santa Barbara channel around Point 

 Conception and then on northward, is only 

 one of the many problems presenting them- . 

 selves for solution on our coast. 



Worthy of note is the discovery made by 

 Mrs. Burton Williamson during the sum- 

 mer while at work at the laboratory, that 

 at least two species of Pecten occurring on 

 the southern coast, viz., P. equisulcatus and 

 P. diegensis are hermaphroditic. A species 

 of gymnosmatous pteropod related to 

 Pneumodermon pacificum Dall, though 

 probably a different species, was taken with 

 the deep plankton net in San Pedro chan- 

 nel in considerable numbers. No species of 

 this genus, excepting pacificum, has been 

 reported hitherto from the California 

 coast, so far as I have been able to ascer- 

 tain. 



Many of the specimens of a species of 



*'The California Species of the genus Nut- 

 talina,' Nautilus, Vol. VII., 1894, p. 133. 



t' Synopsis of the Family Tellinidse and of the 

 North American Species,' Proc. U. S. Nat. Mus., 

 Vol. XXIII., 1900. 



