MARINE MOLLUSCA 557 



having growth-striae only. Both anterior and posterior ends gape widely, 

 and while both are thickened within, neither has a marginal rib. An- 

 terior margin vertical to the hinge-line, straight, curving below into 

 the expanded and broadly, obliquely rounded basal margin; poste- 

 rior margin oblique, a little concave above. Alt. 30 mm., greatest 

 antero-posterior dimension (measured obliquely across the widest part 

 of the valve), 20 mm.; length of hinge-line, 12 mm.; diameter of 

 closed valves, 11.5 mm. From Tagus Cove, Albemarle. 



Lima pacifica Orb. (Z.. arcuata Sowb., preoc.) is broader below, 

 with shorter hinge-line, and the posterior gape is smaller than the an- 

 terior, while in L. galapagensis the gape at the two ends is subequal. 



CHLOROSTOMA SNODGRASSI sp. nov. ' 

 (PI. XXXV, figs. 6, 7.) 



Shell umbilicate, conic with somewhat flattened base, very strong 

 and solid, thick ; of a pale brown or green tint variegated with large, 

 irregular black stripes or flames above, interrupted beneath, the base 

 being irregularly tessellated or speckled. Spire conically elevated. 

 Whorls 6^ or 7, quite convex, the last rounded at the periphery. Sur- 

 face lusterless. Sculpture of somewhat unequal spiral cords of which 

 there are 19 or 20 on the last whorl, most of them, especially several 

 in the peripheral region, being weakly granose ; closely crowded ob- 

 lique lamellas in the direction of growth-lines crossing them, subobso- 

 lete on the summits of the ribs, but conspicuous in the interstices. 

 The aperture very oblique, rounded-trapezoidal, the nacre iridescent 

 within, the lip having a dull white border within the dark edge. Colu- 

 mella short, vertical, thin, and excised, two small contiguous teeth at 

 its junction with the basal lip, another near them upon the latter ; the 

 upper insertion of the columella is produced in a tongue-shaped, in.' 

 tensely green callus partially surrounding the umbilicus. Umbilicus 

 narrow and deep, contracted at the opening. The dimensions of three 

 specimens are: length, 15.5, 13, 17 mm.; diameter 16, 15, 15 mm. 

 From western coast of Albemarle at Iguana Cove, Point Christopher 

 and Tagus Cove. 



Tfcis species is more conic than Chlorostoma reticulatum^ C. ligu- 

 latum, or C turbinatuni. The columellar callus is green, like that of 

 C turbinatum. 



It is, we think, the Trochus itupressus of Fischer, Chlorostoma 

 impressum of Pilsbry's monograph ; but it is not Trochus impressus 

 "Jonas" Fhilippi, which is a synonym of T. corvus "Jonas" Phil., 

 1849. This latter species has radially waved whorls above and other- 

 wise differs from C. snodgrassi. 



