GASTEROPODA. 157 



The aperture is generally longer than it is wide, sometimes twice as long ; a few dis- 

 torted specimens, however, have the aperture transverse. In its young state, the 

 volution of the vertex is on a level with the margin, projecting beyond it ; and this 

 character is sometimes preserved throughout its existence, though, in some large 

 specimens, the vertex is elevated considerably above the level of the base. It is covered 

 with coarse and prominent striae, amounting almost to ribs, with deep sulci between 

 them, and occasionally decussating lines of growth, which are, however, very 

 irregular, and not always visible. The muscular band appears like that in C. unyaricus, 

 but in my specimens it is not always distinct. 



Small and imperfect specimens are by no means rare in the Coralline Crag. 

 In Capulm ungaricus the vertex is generally regular and straight, though occasionally 

 it may be observed to incline on one side. This species appears to have a longer cone, 

 with the vertex always on the right side. The sinuses in variety |3 appear as 

 if they had been produced by the inequalities or rays of a pecten, upon which the 

 animal might have adhered. In my specimens (only three in number) they are upon 

 the left side of the shell, and regular, and if produced in this manner, the animal must 

 have had the power to elevate its right side so as not to be similarly affected, as 

 that side is free from these inequalities ; the striae upon the exterior take a longitudinal 

 or rather a radiating direction from the vertex, and run obliquely across these sinuses, 

 from which it is presumed they are accidentally produced. 



4. CAPULUS FALLAX. S. Wood. Tab. XVII, fig. 4, a b. 



CAPULUS FALLAX. S. Wood. Catalogue, 1842. 



C. Testa suborbiculatd, depressd, lavigatd, tenui, fragili; vertice obliquissime ad 

 dextram revoluto, spiraliter intorto ; margini postico impendence ; basi dilatatd, subovatd. 



Shell suborbicular and depressed, smooth (?), thin, delicate, and fragile, with an 

 involute and very oblique vertex, spirally twisted on the right side, and projecting 

 beyond the base, with an expanded subcircular opening. 



Diameter of aperture, ^ an inch. 



Locality. Cor. Crag, Sutton. 



I have about a dozen specimens of this shell in my cabinet, which, however, are not 

 very perfect, but appear to differ from any of the preceding species sufficiently to 

 be considered distinct ; they are perfectly smooth, without striae, but they are much 

 injured, and cannot be depended upon in that character. The great obliquity of volution, 

 which much exceeds that of C. militaris, is the character which best distinguishes 

 it, and gives it a form approaching to the genus Velutina. Unfortunately, I have no 

 specimen that will show its muscular impression, but the flattened form of the posterior 

 margin, beneath the vertex, shows the capuloid character of the shell ; this obliquity of 

 its volutions gives it a subcarinated form to the left side of the back, and connects this 

 species with the regularly but obliquely spiral univalves. 



