OF CONCHOLOGY. 283 



NOTICES AND REVIEWS 



OF 



NEW CONCHOLOGICAL WORKS 



BY GEO. W. TRYON, JR. 



I.— AMERICAN. 



Synopsis of ths Family Unionidee. By Isaac Lea, LL.D. Fourth edi- 

 tion, 184 pp. 4to. Pbila,, 1870. 



The author states in his preface that during the eighteen 

 years that have elapsed since the publication of the third edition 

 of his " Synopsis," the number of admitted species and syno- 

 nyms has been doubled, showing the great activity of students 

 and collectors in this branch of conchology. In the introduc- 

 tory portion of the admirable review of the classifications of Uni- 

 onidee proposed by former authors, Dr. Lea gives the number of 

 species included in the present volume as follows : Recent spe- 

 cies known to him and admitted to be distinct, 1069 ; 224 doubt- 

 ful species, including those only known through descriptions ; 

 183 fossil species, and 891 synonyms. 



•Following the tables of species and synonyms, which, as in 

 former editions, are arranged under the various genera in groups 

 divided according to differences in form and surface, is a table 

 of Geographical Distribution, which is a great improvement on 

 the tables formerly given, as it gives the names of rivers and 

 States, where formerly the divisions North and South America, 

 Europe, etc., were deemed sufficiently particular. In this list 

 the number of species of Unio inhabiting Europe is placed at 

 nine, notwithstanding the industry with which European provin- 

 cial naturalists have been enriching conchological science for 

 some years by describing most of the Unionidse of their respec- 

 tive neighborhoods as new ! I agree with Dr. Lea in his whole- 



