462 CYPRINIDiE. 



Astarte compressa, Macgilliv. Moll. Aberd. p. 2G1. — Brit. Marine Conch, p. 



247. 

 Crassina compressa. Brown, Illust. Conch. G. B. p. 9G, pi. 3(5, f. 4, 5. 



„ corrugata. Brown, Illust, Conch. G. B. p. 9(5, pi. 40, f. 24, 

 Astarte boreulis, Philippi, Neuer Conch, vol, ii. p. 58, Astarte, pi. 1, f. 11. — 

 Forbes, Memoirs Geol. Survey G. B. vol. i. p. 412 ; Ann. 

 Nat, Hist, vol, xix. p. 98. 

 „ corniguta, Loven, Index Moll, Skandinav. p. 37 (from types), 

 „ plcma, Sowerby, Min. Conch, pi, 179, f. 2, 

 „ Withami, Brown, Wern, Mem. vol, viii. pi. 1, f. 24, 25. 



This scarce and interesting bivalve assumes such various 

 forms, that shape can scarcely be held characteristic in the 

 species ; indeed, it seems somewhat debatable whether the 

 outline of any Astarte is of specific importance. The con- 

 tour, which is almost always somewhat triangularly sub- 

 cordate, is subovate in most adult individuals, as the length 

 in that stage generally exceeds, and very decidedly, the 

 breadth ; but, the immature valves, and certain full-grown 

 ones likewise, have their length and breadth nearly equal ; 

 in which case the hinder termination becomes broad, and 

 more or less triangular, instead of, as in the produced 

 forms, rounded and somewhat tapering. The valves are 

 rarely at all ventricose, and are usually shallow, becoming 

 more rapidly so in front than behind. The sides, although 

 unequal, are not greatly so for the genus, the posterior 

 seldom occupying two-thirds of the entire length. The shell, 

 which is often heavy, and always solid, opaque, and of a 

 lighter or darker rufous tint, is covered by a fibrous chestnut- 

 coloured epidermis, which has a silky lustre, is thinner to- 

 wards the beaks, and becomes thicker, and with the fibres 

 arranged so as to resemble crowded concentric striulte to- 

 wards the lower margin. This latter, which is quite entire 

 within, is arcuated, and rises anteriorly with greater con- 

 vexity and rapidity, generally forming a slight angle with 

 tl>e upper edge. Both dorsal slopes are more or less con- 



