256 AMERICAN JOURNAL 



Lottia onychina, GUI., Moll. U. S. Ex. Ex. p. 355, fig. 4G1, 

 461a, and b, 1852. 



Animal yellowish ; mantle greenish, Avith brown markings 

 upon the border, ciliated; head and tentacles rosy. Hab. Rio 

 Janeiro, Brazil. 



The soft parts of this unpretending little shell agree in all 

 essential particulars with the west coast species. 



COLLISELLA (?') ROSACEA, Cpr. 



Acmcea {? pileoliis var.) rosacea, Cpr., Proc. Cal. Acad. Sci. 

 iii, p. 218, 186(3. 



Common at Monterey (50 sp. Dall), and reported from San 

 Diego. 



The type specimen of this species is now before me. After a 

 careful study of it, I would add to Dr. Carpenter's diagnosis tiie 

 following remarks : 



The shell is small, obtusely conical with an erect, sub- 

 central apex. The ground color of the surface is a trans- 

 lucent white, suifused with rose toward the margin, where 

 several indistinct rays of rose color appear. These are more 

 evident on the inside. The extreme nucleus is usually 

 white. The apex is profusely dotted with minute dark brown 

 and opaque white specks of color, whicii are not rays, nor are 

 they often arranged with any regularity ; these are more nu- 

 merous on the posterior portion of the shell, but vary exceed- 

 ingly, from a dark reticulated brown network of lines to wavy 

 irregular penciilings or sparse brovfn dots, usually most plenty 

 on the interspaces of the ribs. The surface is smooth, especially 

 in front, but from the apex radiate (especially on the posterior 

 half of the shell) a number of very marked riblets which appear 

 as if indented from below, and do not materially interrupt the 

 smoothness of the surface, though the margin is rendered 

 slightly crenulate by them. They are also of a more opaque 

 white than the remainder of the shell, and sometimes form con- 

 spicuous white rays. 



This species is a southern form and has not been found north 

 of Monterey as far as recorded. It is somewhat confused, on 

 account of having been confounded with small dead specimens 

 of Liriola peltoides, (Cpr.) Dall, which have a general resem- 

 blance to it in form and color, though otherwise very distinct. 



The latter much more nearly resembles Acmcea virginea than 

 does the true rosacea, which is a very different shell. 



On comparison, we find that rosacea wants entirely the char- 

 acteristic brown rays of virginea, the apex of rosacea is much 



