Lea's Synopsis of the Naiades. 267 



making some enquiries respecting its origin and progress, the 

 result is highly creditable to the industry and ability of its 

 conductor. 



It appears that the arrival of Hugh Cuming, Esq., into 

 this country, with large accessions to the then known species 

 of shells, gave rise to the first idea of establishing an illustra- 

 tive work, to make them known to the public ; and, as new 

 species are continually occurring, while many other species, 

 which, although known, have not been correctly figured, 

 the work was not likely to be soon at a stand for want of 

 subjects. It was commenced in October, 1832; between 

 which and the present time 118 parts have been published. 

 These, as we learn from a notice on the wrappers, contain 

 about 975 figures of about 678 species and varieties belong- 

 ing to 1 5 genera. 



Mr. G. B. Sowerby, sen., has considerably increased the 

 value the work, by inserting in it, from time to time, com- 

 plete catalogues of several genera, containing references to 

 figures of each species in this or some other conchological 

 work, with descriptions of those species which have not been 

 previously characterised. Catalogues of the genera Cyprae'a 

 Cancellaria, Nucula, Amphidesma, Eburna, Eulima and Fis- 

 surella have already appeared ; and, from the careful manner 

 in which they are compiled, as well as from the eminence of 

 their author, promise to be extremely useful. 



Although we understand, from the titlepage, that the work 

 is intended only to illustrate such species as have not been 

 figured elsewhere, yet it seems that this rule has, in two 

 or three instances, been departed from : for instance, the 

 genus Cyprse^a, the new species of which occupied the first 

 8 parts, is now being continued from Part 101., in order to 

 give the whole of the species, whether published before or 

 not ; thus forming a monograph of the genus. Such parts of 

 the work must, as far as we can judge from our knowledge of 

 the parties engaged, and of the materials which they possess, 

 form the most complete monographs ever published. 



Upon the whole, we feel no hesitation in strongly recom- 

 mending this work, as a desirable acquisition to those who are 

 interested in that branch of natural history which it is in- 

 tended to illustrate. 



Art. III. A Synopsis of the Family of Naiades. By Isaac Lea, 

 Member of the American Philosophical Society, &c. 



The rivers in North America, and especially those to the 

 west of the Alleghany range of mountains, abound with an 

 astonishing variety of species belonging to Lamarck's famijy 



