danger of describing species solely on theoretical grounds as dif- 

 ferent, because they inhabit different parts of tlie world, or as 

 identical from general resemblances. Dumeril and Bibron, in 

 their work on Herpetology, and others, have attempted to identify 

 marine turtles of different waters without sufficient authority. 

 He had himself taken particular pains to inquire about the 

 Sphargis or Leather-backed Turtle, which is found from the 

 West Indies, northward, and which has been taken at Cape Cod. 

 This animal has been said to inhabit the Mediterranean ; but 

 the most thorough investigation shows only seven or eight in- 

 stances on record of its having been found there. The museum 

 at Salem furnishes an opportunity for distinguishing between the 

 imbricata of the West Indies and that of the Indian Ocean, which 

 have been considered the same. Holbrook describes the Trionyx 

 of Georgia as existing in the Northern Lakes, and he traces the 

 exact course by which it could ascend along the coast and up the 

 Mississippi River to the lakes. Prof. Agassiz was satisfied that 

 there are four different species of Trionyx in the United States, 

 three of which are included in the one species of Holbrook ; and 

 that each species has its own limited locality. 



The Chelidra or Snapping Turtles have the most extensive 

 geographical range of any of the Chelonians. The Snapping 

 Turtle of Massachusetts is found in South Carolina, Alabama, 

 Louisiana, Missouri, and even at the head waters of the Osage. 



Of the family of Emydie, E. Blandingii is the true type. 

 The swimming Emyda3 are either Southern or Western species ; 

 there are none in New England except those which have but a 

 limited power of swimming. 



Emys Oregonensis was described by Nuttall as existing west 

 of the Rocky Mountains. Prof. Agassiz doubts its existence 

 west of the Rocky Mountains, because no turtles have been found 

 in those high regions lying between that range and the Sieri'a 

 Nevada. Upon the Alleghanies, turtles have been found at a 

 height of eleven hundred feet only, and there are no indications 

 of their existence above this height. He had received two 

 specimens from localities east of the Rocky Mountains, one of 

 which was brought him by Mr. James M. Barnard, from Min- 

 nesota. Mr. Nuttall's specimen, he thought, must have come 

 from this side of the mountains. 



