ORDER BATRACHIA. 429 



The olfactory nerves come from the anterior extremity 

 of the cerebral hemispheres. The foramen through which 

 they issue from the cranium is double. The tube of the 

 nasal fossa? is represented by a simple hole, and there is no 

 cavity in the parietes of the cranium, or in the thickness of 

 the facial bones, that can be compared to the sinuses in man 

 and the mammifera. In the interior of these fossa3, nothing 

 is found but some tubercles instead of the projecting laminae 

 which furnish those of other animals. The pituitary mem- 

 brane is coloured by a net-work of blackish vessels. The 

 nostrils are tubulous. 



The orbits are not separated from the temporal fossas but 

 by an incomplete osseous branch. Their base is directed 

 upv/ards. The optic foramina are very much separated. A 

 large tunnel-formed auricle embraces the optic nerve, and is 

 divided towards the globe of the eye into three portions only. 

 Two other muscles, one depressor, and the other oblique, 

 serve also for the motions of the eye. The lids are three in 

 number, and are all horizontal. The upper one is a mere 

 projection of the skin; the lower one is more mobile; the 

 third, which moves from bottom to top, is more in action than 

 the others. It is very transparent. The obliquus magnus 

 does not exist. Two small blackish glands lodged in the 

 orbit, seem to occupy the place of the lachrymal gland. The 

 ciliary processes are few in number. The pupil is rhom- 

 boidal. The axis of the crystalline is to its diameter as 

 7 : 8. 



The ear of the frogs is conformed like that of toads, of 

 which we shall speak in its proper place. Gautier has ob- 

 served that the cavity of the tympanum is transversed by a 

 kind of cord, which separates it into two equal parts, and 

 which can stretch at the will of the animal, and to different 

 degrees, the membrane which closes this cavity, and which is 

 apparent externally, smooth, and oval. The tympanic box, 



