Mollusks. 1421 



the same reason with the preceding. The following is its description : shell oblong, 

 irregular, thinnest at the centre, of four irregular arcuated turns, which are strongly 

 striate longitudinally ; having on the outer volution two carinations, one at each edge, 

 a third is sometimes visible in the middle of the last whorl. Aperture produced, con- 

 tracted, strongly wrinkled : the opening oval, with a strong, central emarginate tooth, 

 extending about one-third the height of the mouth, 0.10 inch. My specimens are 

 from oysters and sand from Falmouth harbour. 



Vermiculum simile, (King.) Shell oblong, smooth, thickest at the centre, with 

 four (sometimes five) turns visible on one side, and three on the other : the outer volu- 

 tions rounded. Aperture hardly produced suboval, with a small central emarginate 

 tooth. Length 0.06 inch. In very old shells a small subcarination is some- 

 times visible on the last whorl. It is a critical species bearing some resemblance to 

 Vermiculum bicorne and V. bicarinatulum. From the former, its aperture and the 

 great number of its volutions visible, at once distinguish it : its smoothness, and the re- 

 gularity of its form, as well as its aperture distinguish it from the latter. 



Spiroloculina concentrica ? (Macgillivray). To this species, of which I have only 

 met with three specimens I have affixed a mark of doubt, as those which I have found 

 differ from the only species of this genus hitherto described not only in colour, shape, 

 and the number of its cells,but also in its cells being hardly to be distinguished from 

 each other, there being no visible suture. As I have no specimens of the original spe- 

 cies I think it better to leave it thus than to describe it as new. I shall esteem it a 

 great favour if any of your correspondents can furnish me with a specimen of the ori- 

 ginal species for comparison. 



Arethusa lactea, (Fleming). This rare species I have found on the upper valves of 

 the Pecten maximus from Falmouth : also in shell-sand from the Land's End. 



Arethusa Newnhamiana, (King.) I have thus provisionally named a species 

 which exists in the shell-sand in Falmouth harbour in astonishing abundance. From 

 its congener it is perfectly distinct : shell globular, semi-transparent, with three and a 

 half or four whorls. On the body volution are ten or eleven oblong convex chambers with 

 slight separating depressions. Diameter 0.025. From Arethusa lactea it differs in its 

 smaller size and in the greater number and convexity of its chambers. I have dedi- 

 cated this pretty species to my friend W. O. Newnham, Esq., St. John's College, 

 Cambridge. 



Lobatula vulgaris, (Fleming). This shell is exceedingly common on the upper 

 valves of the Pecten maxitnus. I have found it between tide marks on a living Fissu- 

 rella Graeca, 



Lobatula pulchella ? (Macg.) The shell which I have referred to this species pre- 

 sents some marks of difference from the shell described by Macgillivray. I cannot, 

 however, at present decide upon its distinctness. It is common on the valves of the 

 Pecten maximus, associated with Lobatula vulgaris. 



Rotalia Beccarii, (Fleming). I have found but a single specimen of this shell. It 

 was on a valve of Modiolus discrepans, obtained at Falmouth between tide-marks. 



Rotalia inflata, (Fleming). Not uncommon on oyster shells. I found it also on 

 a Fissurella between tide-marks. 



Polystomella crispa, (Lam.) Common on oyster shells. Its young state differs in 

 one respect so remarkably from the adult shell, that at first I was strongly inclined to 

 think it distinct. The sharp, carinated rim is sometimes in the young shell armed 



