208 Mr. W. Clark on some of the Animals of the Chemnitzise. 



of 5-6 volutions, with a cone of broader basal dimensions ; this 

 is the type, and though usually smooth in the aperture, is 

 sometimes furnished with transverse crense in the throat; I 

 have four which were examined alive in comparison with the 

 smooth ones, and they are, both in shell and animal, iden- 

 tical ; it is difficult to account for the occasional presence of di- 

 stinct crense in the same species. The third form is of the 

 larger size of 6-8 volutions with white shells ; these are smooth, 

 though sometimes furnished with striae in the throat of the 

 aperture ; I have several of each, which are so exactly repre- 

 sented by the figure of Mr. Alder's O. conspicua in the ' British 

 Mollusca,' that I am induced to consider that species as a large 

 crenated Ch. acuta ; and it is not improbable that the O. striolata 

 of the same author, like the Ch. turrit a, of which I have spoken 

 largely in the ' Annals,' N. S. vol. vii. p. 392, may be a striated 

 Ch. acuta, which are all more or less furnished with spiral striae 

 on the volutions. I must observe, that the crenated examples of 

 Ch. acuta must not be confounded with any variety of Ch. co- 

 noidea, as the animals of the two are very different ; and as re- 

 gards the shell, the cone of the one attenuates suddenly, whilst 

 in the Ch. conoidea it diminishes more gradually and tumidly. 



The Ch. acuta is by far the most abundant Chemnitzia of the 

 South Devon coasts, and is taken in the coralline and muddy 

 shelly districts. Independent of the three principal varieties, 

 each varies greatly in the contour and colour of its individuals ; 

 it is, after the Ch. pallida, the most variable of the Chemnitzia. 



Chemnitzia unidentata, Mont. ; Annals, N. S, vol. vi. p. 453. 



I have lately examined many live examples of this species, and 

 have only to request that for " head proboscidif arm'' — 'Nostrum 

 truncate in front, not cloven/' may be substituted. 



Chemnitzia conoidea, Annals, N. S. vol. vi. p. 453. 



Odostomia conoidea^ nonnuU. 



A splendid series of all sizes of this beautiful species has been 

 examined, and I have little more to observe, except that I find 

 it has a slender and tumid variety. 



Chemnitzia plicata, Mont. ; Annals, N. S. vol. vi. p. 457. 



Two hundred live specimens of this, I believe, strictly littoral 

 animal have occurred; and I beg that the following sentence, 

 "but I believe it also inhabits the laminarian and coralline 

 districts," may be erased. 



