ORDER CHELONIA. 79 



as to move its limbs without inconvenience, or, on the other 

 hand, to bring it into close contact with the upper shell, and 

 thus to enclose itself, particularly in the genus Terrapene, 

 within a complete box. At the angles of these valves are 

 small processes of bone, or at least distinct muscular impres- 

 sions, to which the adductor muscles are fixed ; and these in 

 the anterior valve, of SternothcBrus LeacManus^ form long 

 spinous processes. It is obvious, that in the genus Sterno- 

 thaerus, the hinder part of the shell cannot be closed, as that 

 part of the sternum is immoveable. 



" Upon the whole, then,"" adds Mr. Bell, "notwithstand- 

 ing the affinities by which these animals are connected with 

 the Emydes of Merrem, are such as forbid me to consider 

 them as a distinct family, yet the structure which I have 

 been describing is so striking, and appears to me of so much 

 consequence, especially as requiring a considerable addition 

 to, or modification of, the muscular system, that I could not 

 look upon it as forming a less important group than a sub- 

 family, particularly as it includes several subordinate divi- 

 sions with distinct generic characters." 



The following is Mr. Bell's arrangement : — 



Fam. Emydidje. 



Subfam. Sternoth.erina. — Characters are : Toes dis- 

 tinct, with sharp claws. Beak horny ; scales of the disk 

 thirteen. Breastplate consisting of one or two valves, united 

 by a ligament, moving as if on a hinge, and thus capable of 

 partially or totally closing the shell. 



Genus I. Kinosternon, Spix. Breastplate consisting of 

 three distinct lobes, the middle one fixed, to which the ante- 

 rior and posterior, which are moveable, are articulated by a 

 ligament. 



The species are, 1. Shamanum, called by Mr. Bell after 

 Dr. Shaw. 2. Longicaudatum. 3. Brevicaudatum. 4 

 Pennsylvanicum. 5. Amboinense. 6. Nigricans. 



