GASTEROPODA. 



Axis fths of an inch. 



Locality. Red Crag, Sutton, Shottisham. 



The specimen figured is from the cabinet of Dr. Reed, and to this the name of 

 Lachesis magna was attached by Mr. A. Bell, but it appears to me to approach so near to 

 Columbella sulcata, J. Sow., from Walton Naze, see Crag Moll., vol. i, p. 23, tab. ii, 

 fig. 2, that I have given to it the same generic name of that aberrant section of Columbella. 



Our present shell may be described as having an elevated spire, volutions slightly 

 convex, ornamented with five or six rather broad and flattened strise, separated by a fine 

 and narrow line, with a deep and distinct suture ; the aperture is ovately quadrangular, 

 but not so much so as that of C. sulcata ; the columella somewhat concave, and the canal 

 short ; the apex is not quite perfect. 



Since the figure was engraved Mr. Robert Bell has presented me with a specimen of 

 this species, a trifle larger than the one figured, and to this he has given the generic name 

 of Pisania, but I see nothing in the specimen to require (according to my view) a new 

 generic position. 



I have here also given the representation of a shell in my own cabinet (2nd Sup., 

 tab. iii, fig. 11), which I think is a distorted, abraded, and immature specimen of 

 Columbella sulcata. It is ornamented with the same kind of spiral striae, the last 

 whorl (only) inflated, and the volutions are made more convex by decortication. 



Lachesis Anglica, Sup., Crag Moll., Addendum Plate, fig. 7, probably belongs to the 

 same section of Columbella. I do not know what especial character is given to the shell 

 for the generic name of Lachesis. 



Purpura lapillus. 2nd Sup., Tab. I, fig. 13. 



The shell shown in the above figure represents a specimen that has been sent to me 

 with the name of "Buccinum?" but I believe it to be simply a distortion of Purpura 

 lapillus, and as it comes from Bramerton, whence I had previously received many speci- 

 mens of other shells greatly distorted, I am strengthened in this view, and the shell may 

 be classed with other distorted specimens figured in the Crag Moll. ; see tab. iv, fig. 6, 

 and tab. xix, fig. 12. The full-grown individuals of this species, or at least nearly all of 

 them, have the outer lip sharp and simple, but in the young state the specimens are some- 

 times regularly and strongly dentated on the inside of the outer lip. I have other specimens 

 of the same size, and less than the one figured, which have a few and strongly marked 

 denticles on the right side of the aperture, but in general they are absent. The present 

 specimen has been much rubbed and abraded, indicating the shallowness of the water in 

 which it had lived. What should cause this peculiar dentation to the aperture in some of 

 the young shells and not in others I am unable to explain. This character of dentation 



