54 Bibliographical Notices. 



Introduction, the second containing a descriptive account of the 

 British Land and Freshwater Mollusca. 



The Introduction, comprised in six chapters, furnishes much valu- 

 able information condensed into a small compass. It has evidently 

 been drawn up with much care ; and the history, habits, structure, 

 and economy of the Mollusca are well handled. The following ex- 

 tracts will give our readers a fair idea of the contents. On hybridism 

 we find the following information : — 



" Although many surmises have from time to time been hazarded 

 as to the production of abnormal forms of Mollusca by means of an 

 unnatural union between individuals of different species, the only 

 direct experiments or observations that appear to have been published 

 on the subject have been made by French naturalists. M. Gassies, in 

 his descriptive Catalogue of the Land and Freshwater Mollusca found 

 near Agen, mentioned several cases of what he calls ' accouplements 

 adulterins,' which he had observed between individuals of Helix 

 virgata and Helix Pisana, as well as between those species and Buli- 

 mics decollates. M. Gassies enclosed the snails, during a thunder- 

 storm, in a vessel covered with metallic gauze ; and he believed that 

 the electricity with which the air was then charged induced the un- 

 natural union. Great care appears to have been taken to prevent 

 any error in the result, by selecting individuals which had not been 

 previously fertilized, and keeping them, after fecundation, separate 

 from any others. The product of these unions was as follows : the 

 young of H. Pisana had perfectly white shells, their mother having 

 the usual coloured bands ; and the young of H. virgata had shells 

 of a darker colour than that of their mother. In the other case, the 

 product of the Helices which had been coupled with the Bulimus 

 was various. Many had shells which were almost scalariform ; the 

 shells of others were pyramidal ; but the greater part of them had 

 shells exactly like that of their mother. The product of the Bulimus 

 did not differ from their maternal form. M. Gassies had also ob- 

 served the product of a union between Helix nemoralis and H. hor- 

 tensisy in which the colour of the lips of their shells in each case 

 varied indifferently from brown or rose-colour to milk-white. Prof. 

 Lecoq and M. Miergue have celebrated the voluntary nuptials be- 

 tween individuals of Helix nemoralis and H. aspersa, as well as 

 between Pupa cinerea and Clausilia papillaris ; but these unions 

 do not appear to have been blessed with any offspring." 



To these instances of hybridism we may add that we have seen 

 some hybrids which had been bred between Helix Pomatia and H. 

 aspersa by an English conchologist. 



Few subjects have greater interest than the wonderful provision 

 which nature makes for the reproduction of lost members among the 

 lower divisions of the animal kingdom. The following account is 

 given of instances of this phenomenon as evidenced among the 

 Mollusca : " Some Mollusca which had been accidentally deprived 

 of their feet, tentacles, eyes, and even their entire heads, have been 

 known to reproduce them. Nearly a century ago, the experiment of 

 decapitating unfortunate slugs and snails was conducted on a whole- 



