REPTILIA. - 255 



SECTION IT. Reptilia haplopnoa. (Monopnoa FITZIXG., Philodota 



MERR.). 



Branchiae neither persistent nor deciduous. Kespiration solely 

 pulmonal. Body covered with scaly skin or loricate with scutes. 

 Occipital condyle mostly single under the foramen magnum for arti- 

 culation with the first vertebra. Labyrinth in addition to the 

 fenestra of the vestibule also furnished with a fenestra rotunda and 

 a rudiment of a cochlea. 



ORDER IV. Ophidii. 



Cavity of tympanum none. Eyes covered with eyelid, single, 

 immobile, pellucid. (Feet mostly none; vestiges of hind feet in 

 some ; in a single genus two anterior very short feet, in the rest no 

 vestiges of sternum and shoulder-bones.) 



The most obvious character of the serpents is the entire absence 

 of limbs. But if this character were relied on exclusively to de- 

 termine whether an animal of this class belonged to the serpents, 

 the Ccecilice (see above p. 238) also would have to be referred to it. 

 Hence it is necessary to have recourse for a basis to the anatomical 

 characters first brought forward by J. MUELLER (Zeitschr. fur Phy- 

 siologie, herausgegeben von TIEDEMANN u. TREVIRAJTCTS, iv. 2, 1832, 

 s. 222 240), and to refer the genera Anguis, Acontias, and 

 Ophisaurus, notwithstanding the absence of limbs, to the lacertine 

 animals. In this way the genus Chirotes, although it possesses an- 

 terior limbs and vestiges of a sternum, is not separated from Am- 

 phisbcena, but is placed in the order of the serpents; the Amphis- 

 bcence themselves having vestiges of a scapula. (See RATHKE Ueber 

 den Bau und die Entwickelung des Brustbeins der Saurier.) The 

 eye-ball, constantly covered by an immoveable transparent eye-lid, 

 is thus a chief character of this order. 



Whilst anterior limbs are met with in Chirotes alone, in many 

 genera imperfect posterior limbs occur. Internally there is found, 

 close to the tail, yet not united with the vertebral column but at some 

 distance from it, an elongated little bone on each side, which ends 

 below in an articular head by which two small bones that diverge 

 from each other, the one directed downwards the other inwards, 

 are connected. Between the two is situated a somewhat larger bone 

 curved in form of the letter S, as a phalangeal bone which supports a 



