84 Bihliographical Notices. 



as their study ; and for their justification the author alludes to the 

 importance attached to the teeth hi the classification of the entire 

 animal kingdom, considering the anatomy of the mouth in Mollusca 

 quite as important as in any other class of animals. Whether there 

 are also peculiarities in the mouth-apparatus of Bivalves and other 

 mollusks which do not possess any fixed portions and which suck in 

 their nourishment from the tidal currents, the author leaves for 

 future consideration, but considers that by further inquiries much 

 might be learnt on the subject. He is also of opinion that this study 

 of the teeth of Mollusca is of the greatest importance to the malaco- 

 zoologist, for, while it is almost impossible, even in spirits, to pre- 

 serve the soft, perishable bodies of the snails, it is doubly welcome to 

 him to possess a fixed, decided, and easily preserved organ, which is 

 so exactly calculated to establish the relations of the genera. 



Very much has been written on the subject, but the results of 

 these researches are so scattered and so little known, that the author 

 has decided in the present work to collect all that has been pub- 

 lished, and, with the addition of his own observations, so to arrange 

 and illustrate the rich store of materials that every future student 

 may with ease compare his own observations with those of others, 

 and thus distinguish new discoveries from those already established. 

 For this present work he copies all such drawings as relate to the 

 subject, carefully noting the author and the book from which he 

 takes them. 



It is probable, in consequence of the interest which the subject 

 has of late created, that during the publication of the work, much 

 may appear of which the author may not be able to take notice. In 

 order as much as possible to avoid this difficulty, he earnestly begs all 

 who are studying the teeth of Mollusca to inform him without delay 

 of the results of their labours, which he vdll publish (always pro- 

 vided the drawings be true to nature) with the fullest acknowledge- 

 ment of the authorship. 



Finally he proposes, at the close of the work, to write a supple- 

 ment, in which he will make mention of such new discoveries as may 

 have appeared during its publication, or that he may have overlooked 

 in former works, and will feel grateful to any one who will point out 

 any such omissions. 



The part now published is devoted to the teeth of the Hetero- 

 poda, the Pteropoda, and part of the Pulmonata Operculata of the 

 Gasteropoda, and is illustrated with four very clearly engraved 

 plates, each containing many subjects, which, besides showing copies 

 of the various figures which have been hitherto published of the 

 teeth of these animals, contain a number of drawings of teeth now 

 figured for the first time. We must consider this as a very import- 

 ant work, and shall watch its progress with interest. 



As one fact of interest, we may observe that some of the Cyclo- 

 stomidcB figured show a great affinity to the teeth of Proserpinuy 

 described and figured in a preceding Number of this Journal, and in 

 this manner an analogy to the numerous hair-like teeth of the Tro- 

 chidce ; but in these land shells, instead of there being a very large 



