44 THE NAUTILUS. 



each lip ; the spire wholly concealed ; the interspaces are smooth 

 and somewhat wider than the ribs. Length 4.2, breadth 3.0, height 

 2.5 mm. 



Two specimens were obtained with the preceding. Both forms 

 have been submitted to Mr. J. Cosmo Melvill, of Manchester, Eng- 

 land, who now possesses the types of Gaskoin's species, and has given 

 especial attention to the group. He regards both as new. 



Erato oligostcita n. sp. Shell small, very nearly the shape of 

 Trivia atomaria, but not ribbed, of a pale olive green, with the 

 extremity of the canal deep rose pink; spire entirely concealed by a 

 microscopically pustulate layer of greenish white callus ; aperture 

 narrow, very slightly shorter than the spire and not angulate exter- 

 nally behind ; pillar lip with two anterior pliciform and half a dozen 

 small pustular more posterior deposits of callus, the outer lip minu- 

 tely dentate, the teeth smaller in front ; the canal very short. 

 Length 3.2, breadth 2.25 mm. 



Found with the preceding. This is perhaps the smallest known 

 Erato, and while, perhaps, nearest to dwarf specimens of the West 

 Indian E. maugeria Gray, it differs from them in its more rounded 

 form and less trigonal outline, as well as by the pustulated surface. 



The European genus Mysia (Leach) Lamarck, of which the type 

 is Lucinopsis undata Forbes and Hanley, has two right and three left 

 cardinal teeth. A very similar type is found in American waters,, 

 represented in the Antilles by Artemis tennis Recluz, and on the 

 Pacific coast by Dosinia subquadrata Hanley. These forms however 

 differ from Mysia by having three cardinal teeth in each valve. 

 For this American type I propose the name of Cyclinella, and add 

 the following new species to the fauna of the Pacific coast. 



Cyclinella singleyi Ball. Shell solid, nearly orbicular, yellowish 

 white, with an extremely thin periostracum, moderately inflated ; 

 surface with very fine close concentric sulci, giving a silky texture 

 to it ; an obscure depression radiates from the beaks near the pos- 

 terior margin ; lunule lanceolate, defined by an impressed line ; 

 pallial sinus narrow, high, rather blunt, pointing at the umbo ; in- 

 ternal margins plain, the middle cardinals strong, the posterior right 

 cardinal bifid. Length 40, height 39, diameter 22 mm. 



Gulf of California in the Yaqui delta ; Singley. It is smaller,, 

 more convex and solid, with vastly larger muscular scars than 

 C. subquadrata Hanley. 



