KINOSTERNID.E. CXXI. 207 



307. CHELYDRA Schweigger. (xeXvs, turtle ; v&op, water.) 



603. C. serpentina (L.). COMMON SNAPPING TURTLE. Dusky 

 brown ; head with dark spots. L. 25 or more. Canada to Equador, 

 everywhere abundant about water. 



308. MACROCHELYS Gray. (/xctKpo?, large ; ^tXvs.) 



604. M. lacertina (Schweigger). ALLIGATOR SNAPPER. Black- 

 ish ; head with many fleshy slips. Gulf States, N. to Wis. L. 40 

 or more ; " perhaps the most ferocious, and, for its size, the strong- 

 est of reptiles." 



FAMILY CXXI. KINOSTERNID^J. (THE Box TURTLES.) 



Carapace rather long and narrow, the outline usually rising 

 gradually from the front to a point beyond the centre of the shell, 

 then abruptly descending ; the bulk of the body therefore thrown 

 backward ; margin of the carapace turning downward and inward 

 rather than outward ; plastron proportionally large, covered with 7, 

 9 or 11 horny plates, the anterior pah- coalescing into one; anterior, 

 and sometimes also posterior lobe of plastron, often movable upon 

 the fixed central portion ; head pointed ; jaws usually strong ; eyes 

 far forward ; limbs slender ; feet short. 



Turtles of small size, chiefly American. 



a. Plastron with its anterior and posterior lobes nearly equal in length, both 

 freely movable and capable of closing the shell ; posterior lobe emarginate 

 behind, its angles rounded ; carapace without traces of keel in adult. 



KlNOSTEKNON, 309. 



aa. Plastron with its posterior lobe longer than anterior, truncate behind, its 

 posterior angles not rounded ; lobes of plastron little movable, incapable 

 of closing the shell; carapace more or less keeled, at least when young; 

 head very large, with strong jaws ...... AROMOCHELYS, 310. 



309. KINOSTERNON Spix. (*/>, to move ; vrepvov, breast.) 



605. K. pennsylvanicum (Bosc). MUD TURTLE. Shell dusky 

 brown ; head dark, with light dots. L. 4. N. Y. to Fla. 



310. AROMOCHELYS Gray, (opoyuz, odor ; X eXvs.) 



606. A. odoratus (Latreille). MUSK TURTLE. STINK-POT. 

 Shell dusky, clouded, sometimes spotted ; neck with two yellow 

 stripes, one from above eye, the other from below ; head very 

 large with strong jaws ; carapace with traces of a keel, but the 

 plates not imbricated in the adult ; no point at symphysis of upper 

 jaw ; odor strong, musky. L. 6. E. U. S., abundant, W. to N. 111. 

 (Rice & Davis.) 



607. A. carinatus Gray. Plates of carapace overlapping more 

 or less, each one edged with black and marked with radiating black 

 stripes ; neck unstriped ; a point at symphysis of upper jaw. La., 

 N. to N. 111. (Rice & Davis.) 



