REPTILES. 233 



the tailed, on the other hand, the tympanic cavity is wanting; in 

 like manner, it is wanting in the serpents. The membrana tympani, 

 attached behind the quadrate bone, lies free in some, yet in others 

 is concealed under muscles and skin. An external auditory meatus 

 is wanting as well as an external ear; in the crocodiles alone is a 

 vestige of this last present in a fold of skin lying above the mem- 

 brane of the tympanum, which has some resemblance to an eye-lid. 

 In the tailed batrachians and in the genus TypJilops there is a carti- 

 laginous plate by which the fenestra ovalis is covered, as the single 

 ossicle of hearing; to this the base of the stapes in the human 

 auditory organ corresponds. To it in most a long stile-shaped ossicle 

 (columella) succeeds, which in the serpents penetrates amongst the 

 muscles, but in the reptiles provided with a tympanic cavity is 

 prolonged to the membrane of the tympanum, and is mostly attached 

 to it by a small distinct cartilaginous piece 1 . 



The muscles in this class are red, although paler than in birds 

 and mammals. The arrangement of them is much more compli- 

 cated than in fishes, where the large lateral muscle (see above, 

 p. 50) composes the chief mass, extending also over the abdomen. 

 In this respect the Proteids and the larvse of salamanders still greatly 

 resemble fishes, but in other reptiles the dorsal portion alone of 

 these lateral trunk-muscles remains, whilst in the tail only this mus- 

 cular arrangement persists on the under surface also. On the other 

 hand, the system of the intercostal muscles is developed, to which 

 also the straight muscles of the abdomen belong, and the system of 

 the lateral abdominal muscles. On this account, as well as from 

 the development of the limbs in most orders of reptiles, a great uni- 

 formity prevails in the arrangement of the muscles in them and in 

 man, and a common plan in the muscles of vertebrate animals is as 

 unmistakable as in the other chief parts of their organisation 2 . The 



1 Compare, besides SCARPA 1. 1. pp. 23 31, especially C. J. H. WINDISCHMANN 

 De penitiori auris in Ampkibiis structura. Lipsiae, 1831, cum tab. ; see also MUELLER 

 Physiol. n. s. 414 416. (Elements of Physiology, translated by Dr BALT, n. pp. 1-233 

 1235.) 



3 On the myology of the Reptilia, besides the general works on comp. anatomy, 

 may be consulted BOJANUS for the tortoises, D'ATON for the serpents (MusTcelsystem 

 eines Python bivittatus, MUELLER'S Archiv, 1834, pp. 346 364, s. 432 450. s. 528 

 543,) ZENKER (Batrachomyologia, Jenae, 1825, 4to), and especially DUGES (Recherches sur 

 I'osteologie et la myologie des Batraciem, Paris, 1835, 4*) for tne batrachians. Comp. 



