24 REPORT OF THE SECRETARY. 



to whom the paper was referred, Prof. James Hall, in whose posses- 

 sion the specimens now are, states that he had hoped long since to 

 put the memoir in such a form as to do justice to the memory of Dr. 

 Troost, and bo in accordance with the latest views of the subject. To 

 do this, however, required an examination of other specimens, and for 

 this object he had never been able to find time. At present he is 

 engaged in a geological report of Iowa, in which there are several 

 plates of Crinoids, and any which may be identical with those de- 

 scribed by Dr. Troost will be accredited to him. We regret exceed- 

 ingly this long delay in the publication of the labors of one so highly 

 esteemed in life and gratefully remembered in death. It has, however, 

 been caused by circumstances over which we had no control, and which 

 have given us considerable disquietude. 



The new and extended series of Meteorological and Physical Tables, 

 which has been in course of preparation for several years, is at length 

 completed and ready for distribution. It forms a volume of 634 large 

 octavo pages, which may be divided into separate parts, each distinct 

 in itself. A copy of these tables will be sent to each of the meteoro- 

 logical observers, and it is believed that a considerable number may 

 be sold in this country and Europe, from which something may be 

 derived towards compensating the author, Prof. Guyot, for the un- 

 wearied labor and attention he has bestowed upon the work. 



At the request of the Institution, Baron Osten Sacken, of the Eus- 

 sian legation, who has made a special study of Dipterous Insects has 

 prepared a catalogue of the previously described species of this con- 

 tinent, analogous to that of Melsheimer's catalogue of the Cleoptera 

 of the United States, which was published some years ago by this 

 Institution. 



It frequently happens that the same animal is described by different 

 naturalists under different names, and there may be among the species 

 enumerated in this catalogue some of this character, but in the pre- 

 sent state of the knowledge of American Diptera the publication of a 

 complete synonymical catalogue is impossible. Yet a list like the one 

 just completed is an indispensable preparatory work for the future 

 study of this branch of entomology. The catalogue includes the 

 species inhabiting not only the North American continent in general, 

 but also those in Central America and in the West Indies. It also 

 gives the principal localitiee where each species has been found. 

 In a list like this, says the author, completeness is the principal 

 merit ; the symmetrical arrangement is but of secondary importance. 



