THE ANNALS '^'^'^ 



AND 



MAGAZINE OF NATURAL HISTORY. 



[FOURTH SERIES.] 

 No. 10. OCTOBER 1868. 



XXVI. — On the Typical Value of the Lingual Dentition in the 

 right Distribution of the Genera of Gasteropoda into Natural 

 Groups and Families, By JoHN Denis Macdonald, M.D., 

 F.R.S., Staff Surgeon, E.N. 



[Plate XVI.] 



Though many of the weak points of pure conchology liave 

 been brought to light by the study of the lingual dentition of 

 the Gasteropoda, there is yet much more to be accomplished, 

 embracing not only the acquisition of new facts by further 

 research, but the right use of those already in our possession. 

 We are, even now, only sufficiently acquainted with the sub- 

 ject to know that any system of conchology, however plausibly 

 framed, cannot be reliable where this important test has not 

 been brought to bear. It is nevertheless true that the import 

 of the dental characters has been either misinterpreted or not 

 sufficiently taken into account in some of our best works on 

 malacology. It is scarcely to be believed, for example, that, 

 as at present received, the greater number of the genera of the 

 two significant families Muricidas and Buccinidai require reci- 

 procal change of place, the truth of which position will be 

 demonstrated as we proceed with the inquiry. 



Mr. Jabez Hogg, in a paper* lately read before the Micro- 

 scopical Society, quotes a passage from Mr. S. P.Woodward's 

 * Manual of Mollusca,' that I had already transcribed for my 

 own purpose some eight or nine years ago ; but, as that pur- 

 pose does not appear to be infringed upon by the tenor of Mr. 

 Hogg's reasoning, I shall still adopt the quotation in question, 

 as affording a good idea of the commonly received views of 

 classification by the lingual dentition {op, cit. p. 450) : — 



* " On the Lingual Membrane of Mollusca, and its value in Classifica- 

 tion," by Jabez Hogg, F.L.S. &c., published in the ^ Quarterly Journal of 

 Microscopical Science,' No. 31, July 1868. 



Ann. (^ Mag. N. Hist. Ser. 4. TW. ii. 17 



