XIII;] THE FROG. II 



of the handle is ensheathed in bone, while the outer part 

 cartilaginous. The cross-piece is fixed into the inner face 

 the membrana tympani, which is lined externally by tl 

 integument, internally by mucous membrane, continue 

 with that of the mouth through the Eustachian recess. Tj 

 mucous membrane of the tympanic cavity covers only t. 

 ventral face of the columella, over the dorsal face of whi' 

 the posterior division of the facial nerve passes. 



The Tongue. This organ, as has been seen, is fixed on 

 in front to the mandible, and by the anterior half of its ve 

 tral aspect to the floor of the- mouth ; the posterior half ben 

 free and bifid at the extremity. JSl arrow-ended and broa 

 ended papillse (papiUcB filiformes and fungiformes) are sea 

 tered over the whole dorsal aspect of the tongue and a 

 largest in front; small glands lie between these papillae. 



The fungiform papillse contain the ultimate ramificatio: 

 of the glossopharyngeal nerve, and the epithelium coverii 

 their summits is peculiarly modified. 



The Integument. 



No special organs of touch have been observed, but tl 

 integument is remarkable for the immense number of closi 

 set simple glandular ceeca which open upon its surface. 1 

 the swollen integument which covers the base of the inn( 

 digit in the males, large papillee with interposed glands ai 

 developed. 



A singular body of unknown ftmction, the irowspot ( 

 inter-ocular gland, consisting of a spheroidal sac with minul 

 cells, occurs in the integument of the frontal region of tt 

 head. 



Cells containing pigment abound in the integument an 

 undergo remarkable changes of form, the pigment bein 

 sometimes drawn together into a spheroidal mass — at othe 

 times distributed in a radiating fashion. 



