fusus. 327 



lying just under the top which makes a narrow flap. 

 Before leaving the capsule the fry are perfectly formed, 

 with conspicuous tentacles, eyes, and operculum ; their 

 shell has two whorls, the first being smooth, and the 

 other showing a few slight incipient striae. Each cap- 

 sule produces only from two to four fry. The latter end 

 of winter seems to be the spawning-season : on the 26th 

 of January 1861 I examined fresh capsules which con- 

 tained merely eggs immersed in a glairy liquid; and 

 seven days afterwards I found in other capsules full- 

 sized and living young whelks. The spawn and fry 

 have been well described and figured by Baster in his 

 ' Opuscula subseciva/ The sculpture of the adult shell 

 differs according to the locality and nature of the ground; 

 sometimes it is coarse, and at other times scarcely per- 

 ceptible. Specimens from Kiel Bay are stunted and 

 " depauperated," owing probably to the admixture of 

 fresh water from the Baltic. In Shetland and at Ber- 

 wick the fishermen make an elegant lamp of the shell, 

 suspending it horizontally, mouth upwards, by a string 

 round the middle, from a nail in the wall ; the cavity 

 contains oil, and the canal a wick. Now and then giants 

 are seen, 7 or 8 inches long. The body-whorl of the 

 female is larger than that of the male. Chemnitz knew 

 the reversed form as a Crag fossil of Harwich ; and he 

 deplored in moving terms the indolence and apathy of 

 naturalists in not procuring live specimens of this " most 

 delicate monster." It is still very rare. Not only the 

 spire of the shell, but also the curve of the operculum 

 is reversed. I am not aware of any explanation of the 

 phenomenon having been offered on physiological 

 grounds. Many of the spiral mollusca are liable to this 

 remarkable kind of malformation. Moquin-Tandon ha* 

 enumerated 38 species of French land and freshwater 



