152 MALACOZOA. GASTEROPODA. PECTINIBRANCHIATA. 



1 1 . Rissoa trunc&ta. Blunt Rissoa. 



Shell oblong, subturrite, slowly tapering, but with an abruptly 

 rounded tip,- of five turns, which are transversely striato-sul- 

 cate, longitudinally striulate, flattened, but separated by a 

 deeply impressed suture ; the aperture ovate, with the inner 

 margin reflexed ; the colour greyish-white. Length two- 

 twelfths of an inch, breadth about a third of the length. 



Found by Miss Marion Macgillivray among shell sand, from 

 the Bay of Cruden, sent by Mr. Alexander Murray, in Novem- 

 ber, 1842. 



Turbo truncatus. Mont. Test. Brit. 300. PI. 10. f. 7.— Turritella 

 truncata. Flem. Brit. Anim. 303. — Truncatella costulata. Risso, 

 Europ. Merid. iv. 125. PI. 4. f. 57. 



12. Rissoa striata. Striated Rissoa. 



Shell oblongo-turrite, subcylindrical, rather thick, opaque, 

 glossy ; the spire about half as long again as the last turn, 

 convexly tapering, rather obtuse ; the whorls six, rounded, 

 spirally striate, with obsolete ribs at their upper margin, and 

 separated by a deep suture ; the aperture ovate, rather acute 

 behind, the outer lip considerably thickened, the inner thin ; 

 the colour of the exterior pale brown, reddish or yellowish- 

 brown, often with two reddish irregular bands on the last turn ; 

 the mouth brownish-purple ; the peristome white. Length an 

 eighth of an inch, breadth a third of the length. 



Abundant on the rocky coasts. Plentiful in shell sand, on all 

 the beaches, where it is white, and when the reddish bands are 

 present, they are often then more conspicuous. Found also 

 among corallines from deep water off Aberdeen, by Miss Mac- 

 gillivray. 



Turbo striatus. Adams, Linn. Trans, iii. 66. PI. 13. f. 25, 26. — 

 Turbo sex anfractibus reticulatis apertura ovali subrnargmata. 

 Walker, Test. Min. Rar. PI. 2. f. 49.— Turbo striatus. Mont. Test. 

 Brit. 312. — Cingula striata. Flem. Brit. Anim. 307. — Rissoa 

 striata. Johnst. Berw. Trans, iii. 271. 



13. Rissoa gracilis. Slender Rissoa. 



Shell turrite, subcylindrical, of six thin, pellucid, glossy, 

 moderately convex turns, distinctly separated by the rather 

 deep suture ; the mouth about a fourth of the whole length, 

 ovate, oblique, a little narrowed behind, with the peristome 

 complete, thickened externally on the outer lip, thinner and 



