54 



each. The elongation of the tail in our species is 

 alone sufficient to distinguish it. We have always- 

 been doubtful whether the minute granulations on 

 our species were not produced by the sandstone in 

 which it is petrified. 



Upon what authority the A. Hausmanni has been 

 considered as a species belonging to the United 

 States we cannot determine. In the valuable and ex- 

 tensive cabinet of trilobites belonging to the Albany 

 Institute., there are a number of specimens labelled 

 with this name by Professor A. Eaton. If we mis- 

 take not, he mentioned to us that similar fragments 

 of this fossil were sent by him to Brongniart, who, 

 we understand, is the author of the list of trilobites 

 found in the manual of De la Beche. The specimens 

 which have been examined, both in the cabinet of 

 Professor Eaton, and in that of the Albany Institute., 

 are certainly not identical with the figures or de- 

 scriptions published of the A. Hausmanni. Profes- 

 sor Eaton, in his Geological Text Book, at page 3K 

 thus describes his A. Hausmanni: " Tail rounded, 

 and forming the middle of a circular arc whose cen- 

 tre is in the fore abdomen, near the head; covering 

 tubercled or spined. Found in coral rag on the 

 south shore of Lake Erie. Also, in its underlaying 

 grit slate on the Helderberg." Some other trilobites 

 mentioned in De la Beche's list as occurring in the 

 United States, we have not been so fortunate as to 

 meet. 



