390 Ml*. W. Clark on the Chemnitzise. 



tilagiaons flexibility. This rissoiclean variety of Chem. pallida 

 is the parent of the C. albella and C. duhia of authors. We 

 possess them both, besides having had authentic specimens sent 

 to us by Mr. Barlee, for inspection ; the C alba and C. nitida, 

 from their figures in the ' British MoUusca/ and in other works, 

 are, beyond doubt, of the same parentage. I engage to match 

 any of the four species I have named. I conclude, from the 

 ' British MoUusca,' the C. notata, nonnulL, is a variety of the 

 typical "pallida." Montagu's shell, from his figure, is also 

 probably a semistriated "pallida;" one of the varieties with a 

 retired inconspicuous fold, and a produced smooth spine, or 

 polished by attrition. We have here a goodly progeny of, as I 

 believe, six pseudo-species from a single parent : I must be 

 allowed to insist ou this position with respect to C. pallida and 

 its spurious offspring. I think it cannot be subverted. 



Nothing is more common than a littoral and coralline zone 

 variety of the same species ; for instance, Rissoa striata, R. semi- 

 striata, Chem. spiralis, Scalaria clathratula, &c. &c. Sometimes 

 the littoral shell is the larger, and sometimes the coralline zone 

 variety. The C. trwncatula recently rediscovered by Mr. Barlee, 

 at Plymouth, is large and elongated in the deeper zones; but 

 the littoral variety, as with C. pallida, is dwarfish, more slender, 

 and is called by recent authors C. cylindrica. They are un- 

 doubted varieties of each other, and both ai*e the Turbo nivosus 

 of Montagu; with me, Chemnitsia nivosa. As proof, the learned 

 authors of the ' British MoUusca ' have, on the highest authority, 

 pronounced the C. cylindrica to be the nivosa of Montagu ; it 

 follows that the C truncatula, which, without question, is the 

 adult of C. cylindrica, is also the " nivosa " of Montagu : a 

 careful comparison of the opercula of the two has since fully 

 confirmed this view. 



The C. decorata, the C. diaphana, of the obliqua type, and the 

 C. obliqua of Mr. Alder, have been kindly put into my hands by 

 Mr. Barlee, for inspection ; I possess them also ; and after the 

 most attentive examination, both lenticular and microscopic, I 

 can arrive at no other conclusion than that of their identity, 

 exhibiting slight specialties. The C. diaphana is certainly the 

 young of C. obliqua, as the ' British MoUusca ' have determined j 

 the only doubt is the C. obliqua of Mr. Alder, though I think it 

 a lai'ge tumid variety of the C. decwata of authors. The C. War- 

 renii I have not seen ; I have, from its figure, in the ' Annals,' 

 vol. XV., considered it referable to the C. insculpta ; but if it is 

 synonymous with the C. decorata, we shall have four identical 

 species : I propose for them Mr. Alder's appellation of C. obliqua. 



Mr. Alder's C. conspicua, we have it; it is, as the learned 

 authors of the ' British MoUusca ' suspect, a large, strong, elon- 



■ rnm vHiwi'trft" 



