MAXACOZOA. TROPIOPODA. LAMELLIBUAXCHIATA. 255 



impression not " entire," but invaded by a deep sinus, 

 must be excluded frcm the genus, and either referred to 

 Cytherea or kept apart. 



1. Lucina Rudula. WrinJded Lucina. 



Shell orbicular, convex, with numerous concentric narrow 

 rugae, becoming lamelliform at the two extremities ; before the 

 umbones an ovato-lanceolate impression ; the ligament of mo- 

 derate length and sunk; the internal surface subgranulate, 

 dull, white, toward the margin smooth and glossy, with faint 

 radiating striae ; the colour white. 



On the Western coasts of Scotland it attains a diameter of 

 two inches ; but the specimens seen by me on the Aberdeen 

 coasts have been much smaller. 



Not very common, in shallow and rather deep water, off 

 the coast. A specimen foimd by Miss Marion Macgillivray 

 has supplied the above description. 



Venus spuria. Gmel. Syst. Nat. 32S4. — Tellina Radula. Penn. 

 Brit. Zool.; Ed.2. iv. 18L— Tellina Had ula. Mont. Test. Brit. 68. 

 PI. 2. f. 1, 2.— Lucina Radula. Turt. Brit. Biv. 116.— Lucina Ra- 

 dula. Flem. Brit. Anim. 441. — Lucina Radula. Lanik. Syst. v. 

 541 j Ed. 2. vi. 225. 



2. Lucina spinifera. Spinous Lucina. 



Shell elliptico-orbicular, compressed, thin, with distinct con- 

 centric narrow ridges, which at both ends become more pro- 

 minent, compressed, and at the anterior especially project in 

 the form of short spines ; two little-elevated divergent teeth, 

 with elongated convex lateral laminae, in both valves ; inner 

 surface minutely and obscurely granulated, toward the margin 

 glossy and obscurely striated ; the colour white. 



A specimen, four and a-fourth twelfths long, three and a- 

 half twelfths high, from deep water, obtained by me in the 

 Winter of 1841-2. 



It seems to me almost certain that this is only the young of 

 Lucina Radula. 



Venus spinifera. Mont. Test. Brit. PI. 17. f. 1. — Myrtea spini- 

 fera. Turt. Biv. Brit. 133. — Myrtea spinifera. Flem. Brit. Anim. 

 443. 



3. Lucina Idctea. Milk-white Lucina. 



Shell orbicular, equilateral, convex, with numerous concen- 

 tric narrow, rather irregular striae ; the umbones medial, rather 

 pointed, a little incurved ; the dorsal slope nearly straight and 



