THE BATRACHIA OF NORTH AMERICA. 



429 



of the eye, whence it passes along the upper edge of the maxilUxry 

 boue as a well-defined groove extending beneath the tympanum. 

 There is no fold of skin passing over and behind the tympanum, as 

 in B. cateshiana. The tympanum is moderate, subelliptical, with the 

 longest diameter longitudinal, the center above the angle of the mouth, 

 its anterior edge reaching within one-third of a diameter of the eye 

 from the eye. The rim is well defined, being slightly raised above the 

 level of the tympanum itself, which is nearly smooth, exhibiting only 

 a slight granulation in the center. The tongue is broad, short, subor- 



FiG. 109. liana montezumce. Valley of Mexico ; |. 



bicular, and with the cornua distant and quite small; it is free on 

 the sides and behind for two-thirds its length. The internal nares 

 are small, transverse, exteriorly produced into a groove extending some- 

 what obliquely backwards to the edge of the maxillary bones ; their 

 centers nearer the anterior canthus orbitalis than to the exterior nos- 

 trils. The vomerine teeth are situated on two protuberances, which are 

 inclined backwards at an acute angle, and placed with their anterior 

 bases in a line with the anterior edges of the internal nares ; the teeth 

 themselves are few in number, minute, and range obliquely on the pos- 

 terior portion of the crest of the protuberances. The- teeth on the edge 

 of the upper jaw are well developed, and extend to the inner edge of the 

 angle of the mouth. The Eustachian openings are large, and at least 

 twice the diameter of the choante. An external vocal vesicle of con- 

 siderable size is seen on each side at the angle of the jaws, as large as a 

 very large pea after being contracted by alcohol. 



As already stated, there are two distinct ridges of skin, one on each 

 side the back, commencing above the tympanum. They are frequently 

 interrupted, and do not reach the groin. The upper i)arts are gener- 

 ally smooth, but with warts on the sides of the body, where they 

 are iiattened at top; occasional warts are scattered over the back, 



