smith: on the genus astarte. 221 



This species does not appear to attain a large size. The 

 largest specimens exceed in this respect any of A. compressa. yet 

 are considerably smaller than half-grown examples of A. borealis. 



The peculiarity of this species consists in the character of 

 the concentric ridges near the umbones. In this region they are 

 more strongly developed than elsewhere, and indeed they I'arely 

 extend beyond the middle of the valves, the lower half being 

 merely concentrically striated. They have too, a somewhat 

 wrinkled or undulated appearance and are not produced quite to 

 the margins, so that the dorsal areas (the umbones being towards 

 the eye) appear comparatively smooth. In the volume of the 

 Annals I referred to, I suggested the possibility of the A. banksii 

 of Gould (Invert. Mass., ed. 2, p. 125, f 438), being the same as 

 this species. However, I now believe this not to be the case, 

 and that this shell, which is certainly not a typical A. banksii of 

 Leach, is nevertheless a form of the A. cojiipressa. 



In the "Annals" Dr. Jeffreys observes — "I am now satisfied 

 that A. warehami of Hancock is not this species, but the same 

 as Crassiiia depressa of Brown = ^. crebrieostaia Forbes = ^. 

 richardsoni Reeve." This appears to me a most unfortunate 

 "lumping of species," for I imagine at least three of these are 

 distinct. A. warehami is described as elliptical in form, with 

 about sixty fine, close, sharp, regular, concentric ribs. The 

 epidermis is of a pale greenish yellow, and the basal margin of 

 the valves is said to be entire, by which I presume is meant not 

 crenate. 



A. a ebricostata is generally rather triangularly ovate, has 

 from thirty to forty ribs, coarser than those in warehaiui, the 

 epidermis is yellowish or olive-yellow and the valves are crenated 

 within in adult shells. A. richardsonii of Reeve, I consider the 

 same as the variety seniisulcata of A. borealis. It is described as 

 " trigono-orbicularis, convexo-compressa, prsecipue ad umbones, 



