Notes on California Mollusea. 
BY W. H. DALL. • : , 
{From thè Proceedings of thè California Academy of Sciences^ August 21.$L, 1871, 
Voi. iv, Part iv, p. 182.) 
In examining tlie brachiopods in tbe State Geologica! Snrvey colleotion. 
and other collections existiug in California, my attention was directed to a 
shell wbicli has gone under tbe name of Wahlheimia Grayi of Davidson. 
Davidson’s species was orginally described from Japan, and is a true Jf'ald- 
heimia. Tbis Californian species is a Terebratclla, and apjjareutly undescribed. 
Having examined typical specimens of TF, Grayi, I bave no besitation in 
considering thè Californian species as distinct and new. It may be charac- 
terized as follows, from thè type specimen of thè State Geologica! Survey. 
Terebratella occidentalis, Dall. 
Spec. char. Shell, variable in size and shade of color, usually of a flesh tint, 
deeper on some of tbe lines of growtb. Sculptured by radiating ribs variable in 
nurnber (9 in thè typical specimen), witb rather smooth interspaces, only crossed 
by more or less prominent lines of growtb. Hinge line long, somewhat arched 
in thè middle ; area wide, sbarply carinated, fiat, crossed by transverse lines of 
growtb. Apex not prominent, usually eroded. Foranien large, incomplete, 
deltidia widely separated, and differentiated fiora thè area by deep grooves. 
Typical specimen lat. -7.5 in., lon. -6 in. and -2 tbick. 
Habitat, coast of California at Monterey, Cooper and Dall. Catalina Is- 
land, Cooper. Cab. Cala. Geol. Survey No. 6. 
Tbis species closely resembles, in generai appearance, Wahlheimia Grayi, 
Dav., w’ith which it has been confounded. 
My attention having been called to specimens of oysters, which had been 
transplanted over thè Pacific Railroad to thè coast of California, when about 
three-fourths of an inch long, and made during one year a large and healthy 
growtb, I observed a notable difierence between thè new growth and thè old. 
The Eastern species is usually characterized by a white shell, with a rather 
smooth surface, varied by irregular lines of growth, and faint radiating ridges. 
The new growth of thè species transplanted into Californian waters is character- 
ized by purple radiating rays of color, and by very strong radiating folds or in- 
terlocking grooves and ridges. These latter are also characteristic of tbe Cali- 
fornian native species. So it would seem as if thè foreign ones had, in their 
new abode, taken on, to some extent, thè characters of thè natives “ to thè 
manner boro.” It must, however, be noted that tbis has not invariably been 
thè case, but is especially noticeable in thè oysters which had been planted in 
C3rtain localities. A similar peculiarity has been noticed by foreign naturalists 
in thè Ostrea edulif of England, which when transplanted to thè oyster beds of 
thè Mediterraneau, takes on some of thè characteristics of thè native Mediter- 
ranean species (0. cocìdear). These observations are not without interest, from 
their hearing on thè variation of species, and thè various doctrines of evolution 
and selection of organic forms. 
