102 Records of the Indian Museum. [Vol. XY, 



below the eyes. The colour was the same as that of the skin covering 

 the rest of the body. 



Arcifera. 



Famil}'' Bufonidae. — The conditions are essentially similar to those 

 in the Ranidae. 



Bufo. — The tympaimm is distinct or hidden, seldom absent. In 

 B. himalyanum (fig. 11) the tympanic area is a comparatively small 

 structure, in some specimens it was partially covered over by the well 

 developed parotid gland arching over it. 



Cophophryne. — In C. sikkimensis no tympanic area is marked of? 

 externally, but on removal of the skin the tympanic membrane is seen 

 to be quite distinct. 



Family Hylidae. — 



Hyla. — In H. annectens (fig. 12) there is a distinct tympanic area, 

 but in some other species it is absent. 



Family Pelobatidae. — Boulenger described the condition of the 

 tympanum for the only Indian genus Leptohrachium (now united with 

 Meyalophrys) in his original account (3) as indistinct or hidden ; in a 

 later paper (4) for Megalophrys he says " distinct or hidden under 

 the skin." In M. carinense (fig. 13) the tympanic area was seen 

 to be quite distinct, lying very far back. The tympanic membrane was 

 found to lie underneath it, and the annulus tympanicus was found to 

 have shifted to a much lower position, being now supported by the 

 vertical limb of the T shaped squamosal. This position is due to the 

 greatly depressed condition of the head, and with it the great forward 

 inclination of the squamosal bone. 



Summary. 



The structure of the middle ear of R. tigrina is described in detail. 

 A change of the usually accepted names is proposed in view of the pre- 

 sent work. The name of the so-called " tympanic membrane " has 

 been changed to " tympanic area," because the " tympanic mem- 

 brane " is a distinct structure lying underneath the tympanic area 

 stretched over the annulus tympanicus. An account of the tympanic 

 area as seen in a large number of Indian frogs of the various families is 

 also given. 



The condition of preservation of the specimens was often found to be 

 responsible for the distinctness with which the tympanic area was 

 marked off from the rest of the skin ; whereas it was quite well seen in 

 well preserved specimens, it could hardly be distinguished in poorly 

 preserved ones. 



References to Literature. 



1. Ayres, H. — " Vertebrate Cephalogenesis II. A contribution to 

 the morphology of the vertebrate ear with a recon- 

 sideration of its functions." J. Morphology, Vol. 

 VI, 1892. 



