G. GENERAL NATURAL HISTORY AND ZOOLOGY. 303 



of environment are most favorable to the life of the species. 



2. The largest species of a group (genus, sub-family, or fami- 

 ly, as the case may be) are found where the group to which 

 they severally belong reaches its highest development, or 

 where it has what may be termed its centre of distribution. 



3. The most " typical " or most generalized representatives 

 of a group are found also near its centre of distribution, out- 

 lying forms being generally more or less " aberrant" or spe- 

 cialized. 



FOSSIL ELEPHANTS, DOGS, AND DEER OF NEW MEXICO. 



Professor Cope has called the attention of the members of 

 the Philadelphia Academy of Sciences to certain mammalian 

 remains from the iieighborhood of Santa Fe. The spi*cimens 

 exhibited belonged to the Mastodon productus^ which must 

 liave been very abundant in that region. The speaker dwelt 

 upon the peculiarities which distinguished it from Mastodon 

 0/iioticus, and ofave at leno-th the characters of the dentition. 

 The vertebrates found in the Santa Fe marl now number 

 thirty-two, including eleven species of Canis. These are all 

 extinct, with the exception of one species of wolf, the Ca^iis 

 coevis of Leidy. This was believed to be identical with the 

 living wolf, which was considered to be specifically identical 

 with the common dog. Tlie species mentioned originated 

 in the Upper Miocene, and persists to the present day. A 

 new form was described under the name of Canis loheeleri- 

 anits. The number of species of fossil deer found in the 

 formation spoken of was increased from four to six, the two 

 new forms beins: named Dicrocenis trilateralls and Dicroce- 

 rus telmanus. American Naturalist^ October. 



NEW EXTINCT "WOLF AND DEER FROM THE UPPER 



MISSISSIPPL 



Many years ago Professor J.D.Whitney made a collection 

 of the bones of fossil mammals from the lead-crevices and 

 superficial strata of the lead regions of Wisconsin, Iowa, and 

 Illinois, a part of which were enumerated by the late Pro- 

 fessor Jeffries Wyman in " Whitney's Geological Report of 

 the Lead Region of the Upper Mississippi," published in 

 1862. The collections comprised the bones oi \.\\q Mastodon^ 

 Megcdonynx^ and Platygomis^ an extinct species of J5/5o;?, an 



