REPOET OF THE SECRETARY. 27 



special demand for the article, 1,000 extra copies were struck off 

 in pamphlet form for separate distribution. To illustrate this work 

 we have been promised by Dr. Gray, of London, a series of stereo- 

 tj'pe casts from the wood-cuts used in the British Museum catalogues. 

 They were not received in time to be inserted in the report. We 

 shall, however, distribute copies of them to all persons who have 

 received the work in a separate form. 



Mr. Carpenter, the author of these lectures, who is well known to 

 the students in this branch of natural history, has presented in this 

 work an account of the present condition of our knowledge of the 

 molluscous animals, and completed a task which will go far to supply 

 a want which has been experienced by all who have commenced the 

 study of these objects. The only other popular introductory work 

 on shells in the English language of a reliable and representative 

 character, is Woodward's Manual of the Mollusca, from which it differs 

 in some essential particulars, which better adapt it to the object in- 

 tended. It includes an account of the extinct as well as the recent 

 forms. The families and higher groups as well as the genera are 

 necessarily very briefly characterized, but sufficiently so to enable the 

 student, with perseverance and study, to identify the species and 

 recognize their affinities. One of the best features of the work, and 

 which will interest the accomplished naturalist as well as the ele- 

 mentary student, is a table of apparently similar shells belonging to 

 different families or genera; or of shells whose general appearance 

 is similar, but which, on account of more important characters, are 

 separated into widely different genera. It is also proper to remark 

 that the work is not confined to a description of the external covering 

 of the animals, but also includes that of their soft parts. 



The other numbers of the above mentioned series of works on con- 

 chology are still in course of preparation, and will be published as 

 soon as they are completed. 



It was also mentioned in the last report that a series of articles was 

 in preparation to facilitate and promote the study of the entomology 

 of North America. This branch of general zoology is perhaps larger 

 than that of all the other branches taken together. In order to illus- 

 trate this statement we may mention, on the authority of Baron Osten 

 Sacken, to whom we are specially indebted for advice and direction 

 in regard to the best means of promoting this object, that according 

 to the most recent computations, the number of species of insects in 

 all parts of the world, is believed to be rather above than below one 



