192 AMPHIBIA. 



Order 3. BATRACHIA*=ANURA. 



Amphibia of stout form, with naked skin, without tail, with pro- 

 ccelous vertebrce and well-developed extremities. 



The body is short and stout and is without a tail. On the head 

 are the wide mouth and the large eyes, the iris of which has usually a 

 golden lustre. The eye-lids are well developed, and the lower, which 

 is transparent, can be drawn as a nictitating membrane completely 

 over the eye. The nasal apertures are placed far forward on the 

 extremity of the snout, and can be closed by membranous valves. 

 In the auditory organ there is generally a tympanic cavity, which 

 communicates with the buccal cavity by means of a .short wide Eusta- 

 chian tube and is bound externally by a large tympanic membrane, 

 which is sometimes free and is sometimes concealed beneath the skin. 



Only a few of the Batrachia are without teeth (Pipa, Eufo) ; as a 

 rule there are small hooked teeth arranged in simple rows at least on 

 the vomer, in the Frogs and Pelobatidce, on the maxillaries and pr?e- 

 maxillaries also. The tongue is absent only in a small group of exotic 

 forms ; it is usually attached between the rami of the lower jaw in 

 such a way that its posterior part is completely free, and can be 

 protruded as a prehensile organ from the wide mouth. 



Ribs are, as a rule, absent, but the transverse processes of the 

 dorsal vertebrae attain a considerable length. A pectoral and pelvic 

 girdle is in all cases present. The former is distinguished by 

 firm connection with the sternum, the latter by the styliform 

 elongation of the ilium. The hyoid bone in its definitive form is 

 considerably simplified ; the body, is supported by large anterior 

 horns, while the branchial arches on each side are reduced to a 

 single posterior horn. 



In the skin, which is usually naked, glands with an acrid milky 

 secretion are often aggregated in many places, especially in the region 

 of the ear, where they form large glandular projections (parotid). 

 Glandular aggregations occur also on the middle division of the hind 

 legs (Bufo calamita) and on the sides of the body. 



* Rosel von Rosenhof, " Historia naturalis ranarum riostratium," Niiruberg 



1758. 



Dauclin. " Histoire naturelle des Raiuettes, des Grenouilles et des Crapauds." 



Paris, 1 -SOI'. 



Rusconi, ' Developpement de ]a grcnouille commune," Milano, 182H. 



( '. I'.vuch, " Beitrage znr Naturgeschichte and Classification der nacktc-n 

 Amphibien." Wurzb. naturwiss. ZeitscTvr., !S<i2. 



('. P.rurh, ' Neue Beobachtimgen zur Naturgeschichtojder einheimischen 

 Batrai'hier." \\'iir:b. n(itnr)fi. Zettshr.. 1S63. 



A. Eckcr, " Die Anatomic des Frosches.'' P.raunschweig, 18(U. 



