126 Leas Genus Unto, $c. 



cally interesting collection ; lias opened it to the access of his 

 patients and friends, from two o'clock to four, on Tuesdays ; 

 and has produced the present Catalogue as an interpreting 

 guide to the objects contained in it. Some notice of the 

 geological characters of the districts whence the author has 

 collected them is given. The objects are classed, and the 

 positions assigned to the classes are shown in an engraved 

 plan of the latter, included in the pamphlet. See our p. 99. 



Lea, Isaac, Member of the American Philosophical Society, 

 &c. : Observations on the Genus Unio, together with De- 

 scriptions of New Genera and Species in the Families 

 Naiades, Conchae, Colimaceae, Lymnaeanae, Melaniana, 

 and Peristomiana ; consisting of four Memoirs read before 

 the American Philosophical Society, from 1827 to ]834, 

 and originally published in their Transactions. 4to, 242 

 pages, with [numerous] coloured plates. Philadelphia, 

 1834. 



The portion of these memoirs which has been sent to us 

 is commenced at the 135th page, and includes two treatises 

 entitled, " Observations on the Naiades, and Descriptions of 

 new Species of that and other Families ; " and M Observ- 

 ations on Lamarck's Naiades." This portion, it is clear, 

 from the list of contents in the book, is meant to be added 

 to a part or parts which have been previously distributed to 

 scientific friends. The purchase of any, or of all, of the 

 memoirs cannot be made, we presume, unless by the pur- 

 chase of that volume, or those volumes, of the Transactions 

 in which they are included. 



The first of the two treatises named contains figures and 

 descriptions of fifty-five species of bivalve, and of thirty-one 

 species of univalve, shells ; whose characters are expressed in 

 the descriptions, and exhibited in the figures. Of almost 

 every one of the bivalve species three views are given ; one 

 of the outer aspect of a valve, one of the inner, and a view of 

 the hinder aspect of the shell, whose commissure, beaks, and 

 contour are shown by this means. Most of the species are 

 from American localities ; but some have been derived from 

 Europe, and a few from China. 



The " Observations on Lamarck's Naiades " are mainly 

 with a view to synonymy. The author has had an oppor- 

 tuity, in a tour in Europe, of inspecting the collection of 

 shells that was Lamarck's. 



Mr. Lea is distinguished for his attention to shells, both 

 recent and fossil. See VII. 383. 



