CHELONIA. 



i IIKI.ONIA. 





J, Dum. and Bibr. Four toes only on each foot, and all 

 "ty "*"'**" ; carapace and sternum of a tingle piece. There are two 

 special: 



H. artotatut ; IT. tiynalta. 



Pyjru, Bell. Feet each with five toes, the posterior ones with 

 four nail* only; oarapaoe of a single piece; sternum moveable 

 anteriorly. 



Thu genus in the only Land Box-Tortoise; but an nnalogtic 

 (Sttnmtkfrtu) occurs among the Marsh-Tortoises, in the division of 

 Pleuroder* Kl.-liaiw. 



The anterior portion of the plastron of Pysit, which is susceptible 

 of motion, is of very small extent, for it only reaches, backwards, to 



the space of the first 

 two pairs of sternal 

 platen, and conse- 

 quently it is under 

 the strongly indi- 

 cated suture of the 

 Kecinid with the third 

 pair that the elastic 

 ligament which per- 

 forms the office of a 

 hinge is seen. By 

 means of this sort of 

 moveable door or lid, 

 the Pyxii can, by 

 lowering it at will, 

 protrude its head 

 and its fore feet, 

 anil by raising it, 

 shut itself up in a 

 sort of box, for the 

 edges of this hinged 

 operculum closely 

 fit those of the cara- 

 pace, which serve it 

 as a door-case. The 

 animal then has 

 nothing to fear, be- 

 cause its sternum 

 protect* behind, by 

 its enlargement, the 

 space by which the 

 feet and the tail can 

 be put forth and 

 deeply drawn up. 



]'. arachnoida is 

 the only species 

 known. 



'i/i, Belt 

 Feet with five toes, 

 the posterior ones 

 with four nails only ; 

 carapace moveable 

 behind; sternum of 

 a single piece. 



Messrs. Duraon! 

 and Bibron observe 

 that this is the most 

 curious of the family 

 Chersites. The Che- 

 lonians that compose 

 it alone enjoy the 

 faculty of moving 

 the posterior part of 

 tln-ir carapace in 

 order to lower it and 

 apply it against the 

 plastron, so as com- 

 pletely to close the 

 OMeous box behind, 

 as the Pyzidei close 

 theirs before when 

 they elevate the 

 mormble anterior portion of thpjr plastron. But, as we have seen, 

 the mobility of the anterior part of the sternum is in Pyxit due 

 to the presence of an elastic ligament which performs the office ol 

 a hinge, whilst \n Kixijryi the carapace offers no really moveable 

 articulation ; the bones, the vertebra;, and ribs are the parts which 

 bend. In consequence of this elasticity of the bones and their 

 thinness, the carapace can be moved down to approximate the 

 sternum. The sinuous line on which this flexion operates in indi- 

 cated externally by a slight space, which in filled by a sort of fibro- 

 cartilaginoua tissue. This undulated line exists between the ante- 

 penultimate and the penultimate margino-lateral plate. 



The three known species have not, like all the other Chersians, 

 the abdominal plates rmi'-li more extensive than the other horny 

 plates of the sternum, which, joined to the enlargement and the 



Pyzii aradmoidrt, eecn from above 



Pyri* arachnoirlft, Men from below. 



rounded contour of the plastron behind, approximates th. m in a 

 certain degree to Cutitdo, the first genus of the Elodians. There are 

 three specie* : 



A'. Iliimrnna ; K. erita ; 1C. Sdliana. 



Pausanias notices a Land-Tortoise in the woods of Arcadia, whose 

 shell was used to make lyres. 



Family II. KUlians Marsh-TortoUes. 



The habits of the Klodians differ very much from those of th.- ..tln-r 

 three great groups of Chelonians. The Marsh-Tortoises have n 

 slowness of the Land-Tortoises. They swim with facility, and mi land 

 make much quicker progress than the Chersians. Tln-y frr.|ui-iit 

 miall streams whose course is not too rapid, lakes, pond*, and m. . 

 they are not almost entirely vegetable-feeders, like th. <'li.T-i.m- and 

 Thalassiang, but, like the Pobunians, pivy on living animals ; river- 

 mollusks, Anourous and Urodele Batrachians, and Aunelides arc tin ir 

 food. 



The eggs are generally spherical, with a calcareous shell, and whit.-, 

 like those of the other Chelonians. The females deposit thi-m in 

 shallow cavities, which they hollow out in the earth, nearly in the 

 same manner as the Laud-Tortoises; but tin- F.lodians |.r. t'.-r th,' 

 banks of the waters where they dwell, in order that their young ones 

 may the more easily there find refuge from their numerous en< 

 The number of eggs varies according to the species, and pr 

 according to the age of the individuals, for the females are capable df 

 producing fertile eggs for some years before they have attained tlirir 

 full growth. 



Sub-Family 1. Cryptodere Elodians. 



Cryptoderes are not only distinguished from the Pleuroderes by the 

 power of completely concealing their cylindrical neck with its i-KmtM 

 of loose skin under the middle of the carapace; but also by tlirir 

 head, which is nearly equal in width to its height at the occiput The 

 eyes are always lateral, and their orbits so large that the diam<'t< -r !' 

 the cavity nearly equals a fourth of the total extent of tin- minima 

 considered with regard to its length. The jaws of the Crypt. 1, r, . 

 are stronger than those of the Pleuroderes ; sometimes they are simply 

 trenchant, sometimes more or less dentilated on their edges, which 

 are straight, or sometimes sinuous. In the greater number of - 

 the anterior extremity of the upper beak offers a large notch, on each 

 aide of which may be seen pretty constantly a rather strong tooth ; 

 in which case it is rare for the corresponding extremity of thu 

 mandible not to curve upwards towards the muzzle in a sharp point. 

 In short, in such cases the upper beak closely resembles that of birds 

 of prey. 



Sub-Genus 1. The Clausiles. 



Cittudo, Fleming, reformed by Gray. Feet with five toes, the pos- 

 terior with four claws only ; plastron wide, oval, attached to the 

 buckler by a cartilage, raoveable before and behind on the same 

 transversal mesial hinge, furnished with twelve plates; twrir 

 marginal horny plates or scales. 



C.Carolina; C. Amboinentu ; C. trifiuciata. 



Sub-Genus 2. The Gapers. 



C. Europaa and C. Diardii. 



Emi/i, Uum. and Bibr. Feet with five toes, the posterior with four 

 nails only ; plastron wide, imtnoveable, solidly articulated upon the 

 carapace, furnished with twelve plates ; two axillary and two inguinal 

 shells ; head of ordinary size ; tail long. 



1st Group. European Emydrt. 

 E. Catpica ; E. Sigritz. 



2n 1 Group. American Emydet. 



E. jHtnrtularia-, K. mnrmorca, E. jinli-li<H'i, I'. '/'/</, ;i/,!ii,-a, E. ronftn- 

 trica, E. terrain, K. /tin-ltiifnii, K. tr riya/rc, E. dcctnufifn. 1 . 



'., E. Floridana, E. ornala, E. concinna, E. rtticvlata, A'. //"""'", 

 E. picta, E. J3MU, and E. Muhltnbfrgii. 



3rd Group. African Emyt. 



E. Sptriglcri. 



4th Group. Oriental Emyda. 



E. Trijuya, E. Retvaii, /.'. 1/iiiiiiltnnii. E. 7V/i/;;,W, /.'. t,,-tn. /:'. 

 E. crtuticollu, E. tpinota, E. ncdla/n, /.'. t,-i,-iiiala, E. DurattceUii, and 

 t. lintata. 



Ttlraonyje, Lesson. Five toes, one of them without a nail on all tin- 

 feet; sternum solid, wide, furnished with six pairs of plates ; twvnty- 

 five marginal scales. 



T. I*tt<n,ii , 7'. Batka, 



J'l<iti/*r,rntin. '!ray. Head armed or shielded, and too large to. nt Bl- 

 under the carapace ; upper jaw hooked ; sternum wide, immoveable, 

 fixed solidly to the carapace, with short ala? ; three 

 scales; five nails on the anterior feet ; four only on the posterior 1W t ; 

 tail very long, scaly, without a crest 



P. megacephalum. 



"ivra, Dum. and Bibr. Head large, covered with small plates ; 



muzzle short; two barbies under the chin; plast,rn i'nni'>\-eable, 



im, covered with twleve plates; three sterno-oostal scales ; five 



nailn on the fore feet, four on the hind feet ; tail long, surmounted by 



a scaly crest 



