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



There can be no doubt of the Ch. indistincta being distinct 

 from the Ch. interstincta ; we, in our first accounts, thought other- 

 wise ; but the greater number of volutions, the invariable absence 

 of a tooth, the much more diffused lattice-work of the former, 

 and the specific differences of the animals, afford decisive marks 

 of distinction. 



We have examined more than twenty live specimens of the 

 typical species, in comparison, often in the same vase, with forty 

 of the variety ' clathrata' which only differs from the type, as 

 regards the animal, in having the posterior volutions pale pink, 

 that gives the shell the appearance of being of a still paler pink 

 hue, but in fresh shells the colour is a dull pearly white ; this dif- 

 ference in the animals is probably dependent on food : another 

 variation, perhaps the effect of the same cause, is, that the contour 

 of the variety is somewhat less slender than the type ; but the 

 similar number of the volutions, the character of the lattice- 

 work, and of the want of the tooth in the aperture of both, 

 together with the identity of the animals, forbid the differences 

 I have noticed to be considered of more value than of mere and 

 not uncommon variations. 



Chemnitzia pallida, Mont, et auct. 



C. eulimoides, Ann. Nat. Hist. N. S. vol. vi. p. 452 ; vol. vii. p. 389. 

 C. rissoides, Ann. Nat. Hist. N. S. vol. vi. p. 455. 

 Odostomia notata, O. alhella, O. duhia, O. alba, O. nitida, O. ris- 

 soides, O. eulimoides, O. glabratal auct. variorum. 



There is nothing to add to the description in the ' Annals ' of 

 the above species, of which several are now alive before me ; I 

 have only to observe, that having examined the animals of the 

 annexed so-called species, I am bound to add them to the syno- 

 nymy of Chemnitzia pallida ; one, as the papers referred to above 

 will show, of the most variable species as regards the shell ; but 

 the animals of all these spurious articles have the unvarying di- 

 stinguishing character of C. pallida, which is absent from all 

 the other Chemnitzice that can in any way be confounded with 

 this group, — I mean the liberal, though irregular aspersion of 

 many of their organs with minute sulphur-yellow or gold-co- 

 loured spots and points; and above all, the organs of their animals 

 are similar. This species is an inhabitant of all the zones, and 

 receives that impress as to form and size which results from the 

 incidents of the respective locahties ; these causes have doubtless 

 led to the formation of the pseudo-species, which I think only 

 in some cases can claim even the distinction of varieties. 



