58 Bibliographical Notices. 



similarly furnished. It is closely affined to Camptonyx, being 

 intermediate between that genus and Succinea. The two last- 

 named shells sestivate attached to rocks. I am inclined to think it 

 possible that links yet remain to be discovered between all the 

 siphon- and tube-bearing genera, in which the peculiar organi- 

 zatioUj common under various modifications to all of them, is 

 more clearly adapted to the animaPs mode of existence than in 

 the cases mentioned. It is extremely probable that such links 

 may have existed and have become extinct. We can on this 

 hypothesis easily conceive that their living representatives or, 

 on the theory of Darwin, their modified descendents possess the 

 organization, in a more or less perfect condition, which was 

 essential to their predecessors, but is no longer equally necessary 

 to their own existence, and that, in short, the various apertural 

 slits and imperforate tubes of Pterocyclos, Pupina, Alycaus, &c., 

 must be regarded in the same light as rudimentary organs. By 

 this hypothesis, also, we can understand the appearance of the 

 more perfect conditions for communication between the atmo- 

 sphere and the lung-chamber of the animal in widely separated 

 forms, while others closely allied to each of them are more or 

 less deficient in all traces of a similar organization, and the 

 occurrence of a gradual passage from tube- bearing genera to 

 others totally destitute of any modification of the peristome or 

 suture is perfectly natural. The tube of Spiraculum becomes 

 an incision in the peristome in Pterocyclos, the Burmese forms 

 of which are closely allied to species of Cyclophorus like C. calyx, 

 Bens,, which have a thickened operculum and a minute rudi- 

 mentary wing-shaped projection of the outer lip, close to the 

 suture; and from these forms, again, there is a passage to discoid 

 species, like C. stenostomus, Sow., with perfect peristomes. In 

 the same way we may pass from Raphaulus, through Pupinella 

 and Pupina, to Pegistoma, and finally to Callia, and through 

 Cataulus to Megalomastoma. To the subject of the affinities of 

 these various genera, however, and especially of the aberrant 

 AlyccEUS, I hope to refer in a future communication. 

 Bombay, May 1863. 



BIBLIOGRAPHICAL NOTICES. 



A List of the Birds of Europe. By Professor J, II. Blastus. 

 Reprinted from the German, with the author's Corrections. Nor- 

 wich : Matchett & Stevenson. London : Triibner & Co. 1862. 



Professor J. H. Blasius, of Brunswick, is well known to the scien- 

 tific world as one of our very highest authorities on European Verte- 

 brates. His Manual of the Mammals of Central Europe is certainly 

 the best of modern works on this subject ; and the second volume of 



