258 



BULLETIN 93, UNITED STATES NATIONAL MUSEUM. 



Large specimens reach a diameter of 42 mm. I have seen others, 

 containing eggs, not more than 11 mm. in diameter. 



Darwin did not give the distribution of riohescens, but his figure 

 and description appl}^ perfectly to the Californian race defined above, 

 for which I use his name in a restricted sense. Reports of ruhescens 

 from other regions were doubtless founded on other races of some- 

 what similar color or upon erroneously localized specimens. T. s. 

 rufot'uicta is paler, with finer pores, producing finer external sculp- 

 ture; it has a differently shaped tergmn and numerous short teeth on 

 the occludent border of the scutum. It is not closely related to the 

 Californian race. 



Form elcgans Darwin (pi. 61, fig. 2). Outer layer of the wall 

 preserved, except sometimes near the summit; white under a cream- 

 color or cream-buff epidermis, which, when perfectly preserved, bears 

 close concentric fringes of short, delicate hairs ; strongly ribbed, the 

 ribs crossed by fine concentric growth-ridges. Sheath reddish in 

 some examples, and these usually show reddish spots where eroded 

 near the orifice, and if filed, a red layer is found under the white, 

 caused by the colored filling of the pores. Some individuals, however, 

 are truly albino, without red in the sheath or pores, and others show 

 only a few small red spots on the sheath. The opercular valves are 

 like those of tmbescens. The largest specimens seen are 20 nnn. in 

 diameter. 



The form described as var. elegwm by Darwin does not seem to be 

 separable from ruhescem, as there are some transitional individuals. 

 It appears to be a form, perhaps an incipient race, in which the 

 cuticle, with the underlying whitish outer layer, are persistent up to 

 a certain size, as in the Lake Worth Inlet form of squamosa, noticed 

 on p. 255. It is not a stage passed through by all individuals of 7'. s. 

 ruhescem, as I have seen typically eroded and colored specimens only 

 11 mm. in diameter. The exact status of elegans must be determined 

 by observations by those who have opportunity to study and collect 

 them. 



Locality. 



I'arallone Islands, Cal 



Pacific ( irovp , Cal 



San Podro, Cal 



San Diego, Cal 



Do 



South end Cerros Island, Lower California... . 



"West Coast " 



Catalina Island, Cal 



Point Loma, San Diego, Cal 



No locality; on ^fylUus cnlifornianus Conrad , 

 Cape St. Lucas, Lower California 



Collector. 



J. E. Benedict. 



C. R. Orcutt. 

 Dr. Palmer... 

 Albatross 



C. R. Orcutt. 



Notes. 



With form elegans. 



Form elegans. 

 Do. 

 Do. 

 Do. 



