MA1ACOZOA. TROPIOPODA. LAMELLIBRANCHIATA. 245 



inner surface glossy white ; margin plain. Length nine- 

 twelfths, height four-twelfths. 



Not uncommon off Aberdeen, and frequently brought up by 

 the lines. 



Area rostrata. Gmel. Syst. Nat. 3308. — Nucula rostrata. Turt. 

 Brit. Biv. 178. — Nucula rostrata. Flem. Brit. Anim. 402. — Nu- 

 cula rostrata. Lamk. Syst. vi. 58; Ed. 2. vi. 504. 



4. Nucula minuta. Minute Nucule. 



Shell elongated, ovato-lanceolate, compressed, very thin, 

 minutely striulate and with several large concentric convex 

 ridges toward the margin; the posterior end rounded, the an- 

 terior extended, narrowed, and truncate ; the umbones very 

 small, somewhat curved ; two faint nodulose ridges from each 

 umbo to the angles of the truncation ; a distinct cavity under 

 each umbo, and on one side five compressed teeth, on the other 

 seven ; the margin plain ; the outside greyish-white, the an- 

 terior glossy, hyaline. Length two-twelfths of an inch, 

 height a twelfth and a-quarter. 



This species is very distinct from Nucula rostrata, to which 

 however it is nearly allied. Independently of other characters, 

 the cavity under each umbo is sufficient to distinguish it. 



The specimen from which the above description has been 

 taken was found by Miss Anne Macgillivray, in shell sand 

 collected by Mr. Alexander Murray, in December, 1842, at 

 the mouth of the Ugie. 



Area oblonga striata, antice angulata. Walker, Test. Min. Rar. 

 PI. 3. f. 81. — Area minuta. Mont. Test. Brit. 140. — Nucula mi- 

 nuta. Tnrt. Brit. Biv. 178. — Nucula minuta. Brown, Illustr. PI. 

 25. f. 18. — Nucula minuta. Flem. Brit. Anim. 402. 



Family V. — Ctcladina. 



Animal ovate or roundish, more or less compressed ; 

 "with the mantle lobes free beneath, united behind, and 

 forming a single tube, which is internally double ; a 

 compressed elongated, very extensile foot ; two round- 

 ish, widely separated adductor muscles 



Shell subovate, or roundish, subcordate, very thin, 

 concentrically striate, covered with a thin, generally 

 olivaceous, epidermis ; the umbones prominent, obtuse ; 

 the hinge with two or three divergent laminar and thin 

 lateral teeth ; the ligament external, inconspicuous. 



x 2 



