38 AMEEICAN JOURNAL 



rays of color, radiating from the spire. There are no ribs or 

 costse, but occasionally a moderately sharp line or two may be 

 observed radiating from the apex, and impressed, as it were, 

 from below. The apex is lighter than the rest of the shell. The 

 interior is extremely polished and brilliant, and only in dead 

 specimens is the mark of the siphon perceptible without a glass. 

 The external colors are visible within, from the translucency of 

 the shell. The siphonal groove is not visible from the outside, 

 nor does it cause any extension or emargination of the edge of 

 the shell. The aperture is roundly oval and the edge simple. 



Some thirty specimens of this beautiful little species were 

 found dea4 on the Halfmoon beach at Monterey. One was found 

 adhering to the frond of a Laminaria. Dr. Newcomb obtained 

 it at Santa Barbara; Mr. Hepburn at San Diego; Mr. Stearns 

 at Purissima and Lobitas, San Mateo county, Cal. Among a 

 large number of beach shells obtained on the Gallapagos Islands 

 by Dr. Hable, this species was not uncommon ; the specimens 

 were generally thinner, lighter colored, and smaller than those 

 obtained from further North. When this shell was first obtained 

 at Monterey, in a hurried list of species found by me at that lo- 

 cality, I gave it the MSS. name of vernalis, from the bright 

 green epidermis, and referred it doubtfully to the genus Nacella, 

 which it externally resembles. Being called away by other du- 

 ties to a more northern station, the MSS. and specimens were 

 referred to Dr. Carpenter. At first that gentleman was disposed 

 to refer the shell to a lost species described by Middendorf under 

 the name of Acmcea pileolus. As the shell in question has not 

 been found north of San Francisco, it is not probable that Mid- 

 dendorf ever saw it, and, moreover, I am informed that his type 

 specimens do not agree with his diagnosis, and are probably 

 young Acmoeas, while his figures differ from this species. 



Dr. Carpenter called my attention to the mark of the siphon, 

 and a more thorough examination showed that it belonged to the 

 genus Siplionaria. 



A careful examination of the type specimens in the Smithsonian 

 Cabinet has developed the following unexpected coincidences : 



Nacella peltoides, Cpr. (S. I. Cat. No. 4023) is exceedingly 

 minute, but appears to be identical with fhis species. The type is 

 so young that it is almost^ colorless, but the mark of the siphon 

 is perceptible with a magnifier. It is a pity that so inelegant a 

 name must be applied to this pretty species.* 



? Nacella mbspiralis, Cpr. (S. I. Cat. No. 11,847). A careful 



* The nnolear whorls, nsnally broken off, are preserved in the unique 

 type of suhnpiralis, and in the types of peltoides. I also found them on a 

 very few specimens from Mty. and (Jal. Ids. 



