MALACOZOA. GASTEROPODA. PECTINIBRANCHIATA. 135 



rugous whorls j the suture deep ; the aperture circular, the 

 peristome complete, and free ; the colour yellowish-brown or 

 olivaceous, the interior white. Diameter one-twelfth of an 

 inch. 



Found by me in April, 1842, among shell sand on the beach 

 at Aberdeen ; by Mr. Murray at Cruden and Ugie-mouth. 



Skenea depressa. Flem. Brit. Anim. 313. Helix depressa. 

 Mont. Test. Brit. 439. PI. 13. f. 5. Skenea depressa. Johnst. 

 Berw. Trans, ii. 273. 



2. Skenea serpuloides. SerpuUne Skenea. 



Shell orbicular, depressed, pellucid, glossy, flat above, very 

 widely umbilicate, of three convex turns, which are faintly 

 striato-rugose above, and smooth beneath; the suture chan- 

 nelled ; the aperture roundish, angulate anteriorly, the peri- 

 stome complete, but reflexed and adherent behind ; the colour 

 white. Diameter half a twelfth of an inch. 



Found among sand at Fraserburgh by Mr. Alex. Murray, in 

 October, 1 842 ; also in Cruden Bay, and at Ugie-mouth. 



Helix serpuloides. Mont. Test. Brit. Suppl. 147. PL 21. f. 3. 

 Skenea serpuloides. Flem. Brit. Anim. 313. 



3. Skenea divisa. Semistriated Skenea. 



Shell orbicular, depressed, pellucid, glossy, slightly convex 

 and smooth above, umbilicate and spirally striate beneath, of 

 three convex turns ; the suture deep ; the aperture circular, 

 the peristome complete, reflexed and adherent for a short 

 space; the colour hyaline-white. Diameter little more than 

 half a twelfth of an inch. 



Found at Fraserburgh, by Mr. Alexander Murray, in Oc- 

 tober, 1842 ; Cruden Bay, Ugie-mouth, Aberdeen. 



Turbo divisus. Adams, Linn. Trans. Hi. 254. Skenea divisa. 

 Flem. Brit. Anim. 314. 



GENUS 4. LITTORINA, PERIWINKLE. 



In their dismemberments of the Linnsean genus Turbo, 

 authors have differed as to what group ought to retain 

 the original name ; but without entering here into any 

 discussion on so intricate a subject, it seems necessary 

 to state that our common Periwinkle, Turbo littoreus of 

 Linnaeus, is that which has been taken to form the 

 type of the genus Littorina. Some of our species deviate 



