Mr. BELL on two new Genera of Land Tortoises. 305 
to my former theory. The possession at length of a specimen 
of the same species, in which the sternum was uninjured, con- 
firmed its truth, however, by exhibiting a perfect land Tortoise 
with the anterior lobe of the sternum moveable, and capable of 
as accurately closing the shell, as in any species of the fresh- 
water Box Tortoises: PTE 
This peculiarity, so unexpected in the Lahd Tortoises; ap- 
pears to be sufficiently important, connected as it is with à. 
remarkable modification of the muscular system, to require a 
distinct generic appellation, which I propose to supply by the 
name Pyxis. 
The importance of such species as forni a | passage from one 
group to another, and the affinities of which serve to indicate 
the relations whereby the different groups are connected, will 
perhaps be a sufficient excuse for my having dwelt so long on 
the minute circumstances connected with the history of cs 
species which form the subject of this paper ; especially when it 
is considered, that in the present instance they fill up a Aiatus 
which has long interfered with a perfect knowledge of the na- 
tural arrangement of the order. 
Ordo. TESTUDINATA, Merrem. 
Fam. ‘TesTuDINID2. 
Genus. PYXIS. 
Pedes clavati ? P 
Testa gibba... : 
Sterni lobus anterior mobilis, ligásnonto articulatus. 
Pyxrs ARACHNOiDpEs. Tas. XVI. Fr 12: 
Habitat | 
Mus. nostr. 
