No. 50.] 59 



show that the material is as durable as it is otherwise well suited for fortifica- 

 tions; being firm enough to withstand a cannonade, yet soft enough to be pene- 

 trated by balls, which become imbedded in it, without producing any extended 

 fracture or material injury. As it is, however, porous and pervious to moisture, 

 it probably would not stand severe frosts; and would not therefore be available 

 for mihtary uses, except within the limits in which it is produced, or in tropical 

 latitudes. 



FEOM F. CAILLIAUD, 



DIRECTOR OF THE MUSEUM OF NATURAL HISTORY OF THE CITY OF NANTES IN FRANCE. 



[ Through M. Vattemahe.] 



A specimen of Micaceous Gneiss, perforated by the Pholas dactylus. 



From Pouliguen on the coast of the Department of the Loire-Inferieure^ 

 with a shell of the Pholas. Discovered by M. OAiLLiAtrD on the 26th of 

 October 1851. 



This beautiful and very rare specimen is accompanied with a pamphlet 

 on the subject by M. Cailliaud, in which he contests the idea that these 

 perforations are altogether chemical, and asserts that they are also me- 

 chanical. 



From Gen. SPINNER, of Mohawk, Montgomery county. 

 A box containing a suit of the Fossils of the Utica slate, a characteristic 

 specimen of the Tkenton limestone, and a specimen of Petsified 

 Moss. 



The following is an extract from Gen, Spinnbk's letter, which ae- 

 companied the box : 



"Mohawk, December 20, 1853. 

 Dear Sib — I forward you, by the American Express Company this day, a 

 box containing a suit of the fossils of the Utica slate, a characteristic specimen 

 of the Trenton limestone, and a beautiful specimen of petrified moss. I have 

 discovered a fine locality of the Utica slate near by, where I can get the fossils, 

 and will hereafter send you more and better ones! " 



The late day at which the fossils were received, is the reason why a catalogue 

 of them is not now given, but a full description of the same will be inserted in 

 the next annual report. 



