-'SO UEPTILIA. 



THE THIRD ORDER OF REPTILES. 



Tllli: SERi'l'XT.S (Oi'iiiDiA). 



These have no feet, and are consequently, of all others, the Reptiles -which most merit the 

 name. Their extremely elonG;ated hody progresses by means of folds pressed backwards against 

 the ground. They divide into three hnnilies. 



THE FIRST FA:\ITLY OF OPIIIDIAXS,— 



ThIC Oll\'ETS 



Ih'tains thf skull, teeth, and tongue of tlic preceding group of .S'-^^^, and the eye has three lids, &.C. 

 \vlience they are merely Seps '.vitliout f'jct. Sueli are 



Tni: Orvets {Angvis, Lin.), — 

 Externally cliaracteri'/.ed by imbricated scales, "wliicb cover tlicm all over. We subdivide them into 

 four subgenera, the three first of which have a shoulder-bone and pelvis beneath the skin. 



The Paeudopocles (Pjf/((fo^ui, Merrem) have the tynipnnum visible exteniallVj and a small prominence on each 

 side of the anus, ^vhich contains an ossicle analog'oas to a femur, articulateil to a true pelvis beneath the skin ; 

 the anterior limbs are only represented by an inconspicuous depression, and have no internal humerus. One of 

 the lun2:s is a fourth shorter than the other. The scales are square, thick, and semi-imbricated, and between 

 those of the upper and lower parts is a fjroove of smaller scales on each side. 



The Ophisaurs {Ophisannis, Duud.). merely differ in the absence of external rudiments of limb$, but retain the 

 tympanum, and have one luno; a third shorter than the other. 



The Orvets (-J/j(7ff/*-, Cavier), have no trace of limbs externally visible, and their tympanum even is couched 

 beneath the skin ; their maxillary teeth are crooked and compressed, and they have none on the palate. The l^ody 

 is surrounded with imbricated scales, without any lateral fold, as in the preceding^ ; and one of the lungs is shorter 

 by lialf than the other. [A species, known as the Sloic-u-onn, or B/ind-worm, is of common occurrence in Britain, 

 and throughout F.urope. When alarmed, it constricts its muscles, and is then singularly bi-ittle.] 



Tliese three subgenera have still an imperfect pehis, a small sternum, scapulars, and also clavicles, hidden 

 beneath the skin ; and the absence of these several bones charactei-izes 



The Acontias {Acon/ia, Cuv.), which, in the structure of their head and eye-lids, still resemble the preceding ; 

 their anterior ribs are connected all round, beneath the trnnk, by cartilaginous prolong;itions ; and they have one 

 middle-sized lung, and another very short one. Their teeth are small and conical, and I think that 1 have per- 

 ceived some on the palate. They are easily known by lia\ing the muzzle closed by a sort of mask. 



THE SECOND FAMILY OF Ol'lIIDIANS,— 

 Tui: True Serpents, — 

 Which is much more numerous, is composed of genera with tieitber sternum nor vestige of shoulder, 

 but the ribs of which still encircle a great jiart of the trunk, and the vertebra' are still articulated by 

 a convex facet applied to a concave facet of the succeeding one. Tiiey have no third eyehd, nor 

 tympanum ; but the i>mrill bone of the ear exists beneath the skin, and its handle passes behind the 

 tympanic Imni'. Scvr'ral have itKo, unih^r llic skin, a vestige of hind-hnilis, which in some even shows 

 itself externally in the rnini of a \niall Inmk. 



AVc subdi\ide them into twii t)il.)es. 



That of the IJoublk-Marchkurs [which progress either liead or tail foremost,] have still the lower 

 jaw fixed as in all the preceding Keptih''^, hy a l}ni|>auie hone, articulated direct to the cranium, the 

 two rami (if ihi^, jnw aneh^lo^ed ,it the s_\ )ni)liysi^, and tlmse of the upper fixed to the skull, and to 

 the intermaxillaries ; so that their swallow cannot dilate as in the following tribe, and their head is of 

 even size with their wdiole body; a form whicli euahles them to progress backwards or forwards with 

 the same facility. The bony fr.une of the orbit is inconiidcte behind, and tlie eye is very snialh 

 Finally, their body is covered wilh scales, tlic anus very near its extremity, the trachea long, and the 

 lieart placed far backwards. None of them is kmjwn to he venomous. 



There are twe> genera, one of which apiiroxiiuates to the Chalcides and Einu^nes, and the other to 

 the Orvets ami Acontias. 



TifE Ampiiisb-enes {Amphisbd'iia, Lin.) — 

 Have the whole body surrounded with circular ranges of square scales, as in the Chalcides and Eimanes 



