On the Perilymphatic Spnccs of the Amjiliihiun Ear. 231 



the immaturity of my specimen. The small size of Triton taeniaf,us 

 rendered it impossible to attain certainty on this point. In view of 

 the statements and figures of Kuhn (1. c.) there is little doubt that 

 most of the Urodela resemble Salamandra maculosa in this respect. 



The perilymphatic spaces in Salamandra maculosa differ very 

 slightly from those of Triton taeniatus, though certain parts are more 

 clearly shown in the former owing to its much greater size. This is 

 especially the case with the recessus partis basilaris, which arises from 

 the ductus perilymphaticus and runs directly backwards and downwards 

 to the pars basilaris. To the inner ventral surface of this its wall is 

 closely applied. Just before reaching the pars basilaris it is completely 

 surrounded by the above mentioned "Spindelknorpel", which is in this 

 region considerable in amount; the portion forming the "Knorpel- 

 rahmen" is continuous with that surrounding the recessus partis basi- 

 laris, as well as with that supporting the wall of the lagena (flg. 13'). 

 The recessus partis neglectae resembles that of Triton, as does also 

 the recessus fenestrae vestibuli. There is however in the Salamander 

 a diverticulum of the spatium sacculare which suggests the ductus and 

 Saccus fenestrae ovalis, described by Eetzius in the Anura. 



Siredon pisciformis may be dismissed in a few words. There is 

 no recessus fenestrae vestibuli. The ductus perilymphaticus is wider 

 and pursues a much straighter course than in the two previously des- 

 cribed forms. The spatium meningeale is relatively more extensive 

 than in the other cases, and its boundaries appear to be less definite 

 (%s. 7, 12). 



The perilymphatic system agrees in all essential respects in the 

 above three species. From Retzius' descriptions of the ductus peri- 

 lymphaticus in several other Urodela, the condition is probably much 

 the same throughout the group. 



The most striking feature in the perilymphatic system is the 

 association of the spaces with the sacculus, pars neglecta and pars 

 basilaris respectively (figs. 6, 13, 13'). It can scarcely be doubted 

 that the function of the thin membranes separating perilymph from 

 endolymph, and stretched in each case across a rigid frame, is connected 

 with the function of hearing. The arrangements are such that vibra- 



