Dr. A. Giinther on the T'aiUess Batrachians, 65 



covers the tympanic region, and the tympanum hecomes visible only 

 after the skin is removed. The tympanum is indistinct in those 

 Batrachians where the skin of the body is firmly adherent to the 

 tympanum, covering more or less of its surface. But in all these 

 Batrachians the tympanum is present ; and it is a great mistake to 

 confound the characters of a hidden and of an absent tympanum ; 

 and much trouble and much misunderstanding would be saved to 

 naturalists, if a more precise mode of expression were introduced 

 into the descriptions. Secondly, we are obliged to acknowledge the 

 value of the development of the ear in systematical arrangements, 

 when we consider that this organ gradually returns to simplicity in 

 the series of the Vertebrata, and that especially in the next class, of 

 Pisces, it obtains systematic importance again. Therefore, though 

 not accepting the structure of the ear as the first principle for the 

 division of those animals, I shall combine it with the dentition. 

 Tschudi discredited Mliller's observation, vindicating for all Anura 

 eustachian tubes and a cavum tympani, and only referring variations 

 of the aperture of the eustachian tube in the cavum tympani to the 

 age of the individual {Bombinator igneus) . Besides he mentions 

 frequent examinations of the structure of the ear, according to which 

 this organ, especially among the " Botnbinatoridce,'' is liable to great 

 variations, nearly in every genus, as regards the form and situation 

 of the ossicula auditus, the chorda tympani, the tympanum, the tuba 

 Eustachii, &c. It is a great pity that Tschudi never published 

 these examinations ; but in those which he has published I cannot 

 quite agree with him. 



The imperfect development of the ear I have found or recognized in 

 Bombinator igneus, Pelobates fuscus and cidtripes, Alsodes monti' 

 cola (Wiegmann in Telmafobius peruvianus), Micrhyla achatina*, 

 Phrynisciis nigricans, IcBvis and cruciger, Brachycephalus ephippium, 

 Ilemisus guttatus {Engystoma guttatuni, Rapp), and finally in Rhi- 

 nophrynus dorsalis, which, although not belonging to the OpistliO' 

 glossa, may be mentioned on account of the structure of the ear. 

 In all these Batrachians, tympanum and cavum tympani are entirely 

 absent ; the eustachian tube is either entirely deficient, as I found it 

 in Phryniscus cruciger and Rhinophrynus (and according to Miiller's 

 observations, perhaps in some specimens o^ Bombinator igneus and 

 Pelobates cultripes), or it is only a blind tube without osteum tym- 

 panicum. Although I always found in some specimens of the same 

 species the same development of the eustachian tubes, I do not ven- 

 ture to contradict other observations, according to which these tubes 

 were found more or less accessible ; and Tschudi may be right in 

 stating a variation to occur with the age. But such a variation as 

 regards abolition certainly would not reach the cavum tympani or the 

 tympanum ; and therefore I hold to the truth of the fact that in the 

 aforesaid Batrachians this part of the ear is wanting. In Bombinator 

 and Pelobates I have always found the osteum pharyngeum of the 

 eustachian tube open. It is situated quite on the side of the pharynx, 



* Cf. Tschudi's « Batrachia,' p. 14. 



Ann, ^ Mag. N, Hist, Ser. 3. Vol'm. 5 



