inhabiting the seas of Great Britain and Ireland. 333 



the aperture " superne subplicata," is another case to show the 

 fallacy of this distinction. 



There can be no objection however to make them subgenera if 

 it be considered desirable to adopt that mode of classification. 



From Mr. Lowe's description (in the Proceedings of the Zoo- 

 logical Society) of the animal of his genus Parthenia, which is 

 identical with that of Chemnitzia, it would appear not to differ 

 from that of Odostomia except in having the tentacula " basi 

 coalita ;" but as the position of the eyes is described by that 

 author to be the same, " superne ad basim internam positi," the 

 account of both animals may be consistent with each other. 



Mr. Alder, in his Catalogue above-mentioned, says that, ac- 

 cording to his observations, " the animal of Forbes' s genus Eu- 

 limella is essentially the same as that of Chemnitzia, and that .it 

 only differs in the more polished surface of the shell." 



Professor Loven in his ( Index Molluscorum litora Scandinavise 

 occidentalia habitantium' (published in 1846) has united all the 

 species noticed by him under the name of Turbonilla of Leach ; 

 but that name was only published by Risso in his ( Histoire Na- 

 turelle de PEurope Meridionale' in 1826, being eight years sub- 

 sequent to the publication of Dr. Fleming. 



The tooth or fold on the columella or pillar of the shell is, as 

 I have before remarked, one of the distinctive characters of the 

 genus, and in this respect as well as the general form of the 

 shell it bears rather a close analogy to the genus Pyramidella of 

 Lamarck. 



Another character which appears to be peculiar to this genus 

 (if we perhaps except Ianthina), and which is found in almost all 

 the species, is that the two first-formed whorls are ab ovo hete- 

 rostrophe, and subsequently reflected on the next. The figure 

 29 of Walker (Test. Min. rar.) is a tolerably correct, although a 

 rude, representation of this peculiarity of form in the fry of 

 Odostomia spiralis; and in pi. 10. fig. 2. of Mr. Wood's ( Cata- 

 logue of the Crag Fossils ? it is well delineated with reference to 

 his Chemnitzia rufa. Montagu also remarked it in his descrip- 

 tion of Odostomia laciea {Turbo elegantissimus, Mont.), as well as 

 Loven in his description of the shells forming his genus Turbo- 

 nilla. 



Although I have examined many hundred specimens of Odo- 

 stomia from almost every part of the kingdom, I have only once 

 met with a reversed shell, and which I referred to the Turbo Icevis 

 of Walker (fig. 35) ; but the specimen was unfortunately broken 

 after having been many years in my cabinet. I considered it to 

 be a monstrosity of Odostomia pallida. 



I do not propose to refer to Nyst (Coq. foss. de Belg.) or any 

 other work on fossil shells except that of Mr. S. V. Wood on the 



