SCIENCE-GOSSIP. 



ment of the basal plates is strongly suggestive of 

 Helix, and in an unstained preparation the whole 

 thing looks utterly unlike Zonites, but the transition 

 is as abrupt as can be wished. 



Conulus fulvus (fig. 7) introduces us to a new state 

 of things. There are eight distinct laterals, and 

 so far, except in their number, no great devia- 

 tion from the Hyalinia type : but the marginals 

 are now very distinctly bicuspid, and their basal 

 plates are elongated in an opposite direction to 

 that usual with the 

 species we have been 

 discussing. This kind of 

 basal plate is what we 

 meet with in the regular 

 Helicidse and the 

 Pupidae. 



To return to the 

 laterals. In cellaria (fig. 1) 

 and alliaria (fig. 2) there 

 is an endocone and a 

 mesocone. In the second 

 group, represented here 

 by fura (fig. 3) and 

 nitiiula (fig. 4), there is a 

 mesocone and an ecto- 

 cone ; but in Conulus we 

 have all three points 

 distinct. There is a 

 slight indication of the 

 endocone in Agriolimax 

 (fig. 5). It is practically 

 important not to confuse 

 these points with the 

 edges of the basal plates, 

 as is easily done if 

 the preparation is not 

 stained. 



The curious conti- 

 nental species, Calcarina 

 candidiistma. Dr., was 

 placed with some hesi- 

 tation by Moquin-Tandon 

 amongst the Zi.mln 

 shows samples 

 from its radula, and it is 

 pretty safe to say that if 

 allied to Hyalinia at all it 



must be a very distant cousin The figure shows 

 the form of the teeth, as usual, at the newly-formed 

 edge of the odontophore, and though they certainly 

 suggest v,me amount of detrition this is not 

 actually th<: u« I ig ', hows the teeth of 

 ii ftlluiida. Mull. There is a good deal of 

 general resemblance to Conulut, both in numbers 

 and in form ; but the marginals are more 

 .id in the form of their basal plates, and 

 the transition i . mora abrupt 



It is not proposed to found any hasty gene- 



Odontophorks of Mom.usca, 



Fig 



:■ 7. 



fig. g, Vitrina pettiuiita 



5, Ai;riolimax laevi: ; fig, r>, Pollta excavata; 

 1 onutus/ulvus; fig. H, Calcarina candulissima ; 



ralizations on the foregoing facts. My object is 

 rather to demonstrate to such fellow snail-hunters 

 as may read these pages, what an interesting field 

 of study is here opened, and to suggest, if I may 

 venture, that it may be patronised more largely. 

 It may be worth while to add that of all distinctive 

 characters which I have yet examined in a com- 

 parative way, the odontophore seems to offer the 

 most constant. It would be absurd, of course, to 

 classify according to tongues only, but we 

 certainly ought to amass 

 and arrange all the in- 

 formation we can about 

 this interesting organ. 

 There is much work to 

 do, especially as too 

 many of the old records 

 on the subject are in- 

 adequate because of 

 imperfect microscopical 

 methods. 



As most people are 

 aware, we find the minute 

 structures of animals less 

 liable to variation than 

 the parts which are, on 

 account of their size , 

 more in evidence. Thus, 

 amongst the snails, of 

 whose radula^ we have 

 spoken above, it would 

 be quite easy to find a 

 specimen of H. radiatula 

 bearing a sufficiently 

 close resemblance to 

 ullaria, to deceive any 

 naturalist who had not 

 given the genus his 

 special attention. Such 

 instances might be multi- 

 plied almost ad lib, for 

 they seem to occur in 

 every part of the animal 

 kingdom, but more 

 especially amongst inver- 

 tebrates. The explana- 

 tion appears to be thai 

 there has been a great 

 deal of convergence of typical form with respect 

 to the exterior characters, a convergence pro- 

 duced doubtless by similar climatic conditions; 

 while those parts of the animal which are not 

 concerned with protection or climatic adjust- 

 ment retain for the most part their primitive 

 Organization, These are matters of detail which 

 mill require close study, and that study should 

 be diligently pursued by all naturalists who take 



an interest in the Invertebrata 



CI o bt continued,) 



B 3 



