264 Zooloyxcal Society : — 



toes weak, slender, covered with small scales above, niul very Ijroadly 

 webbed . 



1, Pscudemys concinna. 



2. P. seiruta. 



The genera Batagur and Malachmys have nearly similar feet, and 

 they ajipear, like Pseudemys, to be the most aquatic animals of the 

 family. 



The species which have hitherto been referred to the genus Cistudo 

 differ considerably in their habits, some being nearly terrestrial and 

 others almost exclusively aquatic. The examination of the animal 

 shows that there are good external characters by which they may be 

 divided into natural groups agreeing with their habits and their 

 geographic distribution. 



I. The more terrestrial have the front of their legs covered with 

 thick, imbricate, triangular scales, the toes only slightly webbed, 

 and the stenmm broad, hiding the legs when withdrawn, as — 



1. Cistudo. 



The head rhombic, the forehead flat, and eyes lateral : confined 

 to N. America; as 



C. CdroHnensis, with four, and C. Mexicana, with only three toes 

 on the hind feet. 



2. LUTREMYS. 



The head oblong, depressed, with the eyes on the upper part of the 

 cheek. Found hi Europe, as L. Europcea. 



II. The more aquatic kinds have the front of the legs covered 

 with small scales and some broad, transverse, lunate plates ; the toes 

 webbed. They are confined to Asia; as 



3. CUORA. 



The head rhombic, the eyes lateral, the sternal lobes broad, hiding 

 the legs when contracted, as C. Amboinensis and C. trifasciata. 



4. Cyclemys. 



The head depressed, eyes subsuperior, the sternal lobes rather 

 narrow, not hiding the legs when contracted, as C. dentata and 

 ('. p!iityitol(t. The latter species was referred to the genus Testudo 

 l)V F. Miiller, and when I first described it I considered it as an 

 Eniyn, but the examination of a series of specimens of different ages 

 shows that it is a species of Box Tortoise nearly allied to C. dentata. 



It has been hitherto believed that there was only a single species 

 of the genus Kixosternon, as now restricted, found in the United 

 States ; and all the adult specimens I have received from that country 

 are, I must own, exceedingly alike, so much so that I cannot under- 

 take to say that we have adult specimens of more than a single species. 

 On examining the young specimens of this genus from the United 

 States, in the Museum (Jollection, it is evident that there are at least 

 three most distinct species found in that country, which probably in 



