Art. XVII. — On the Variations in the Spinal Nerves 

 of Hyla aurea. 



By Miss Geokgina Sweet, B.Sc. 



(Communicated by Professor Baldwin Spencer). 

 [Eead 12th November, 1896.] 



During the years 1893 and 1895 there appeared two papers by 

 Dr. Hermann Adolphi, on the Variations of the Spinal Nerves 

 of three of the European Anura, Bufo variabilis, Pelobates 

 Jitsa/s, and Rana esadenla. Comparatively little being known of 

 the more minute details in the morphology of the Australian 

 Amphibia, it was the wish of Professor Spencer that I should 

 undertake a similar work in connection with some of our 

 Australian forms. Accordingly, in April of this year, I 

 commenced my observations on the nerves of Hyla aurea, the 

 common green frog of Victoria, in the Biological Laboratory at 

 the Melbourne University, and my thanks are due to Professor 

 Spencer for his kindly help and advice given during the progress 

 of this work. 



On each side of the spinal column there are given off generally, 

 ten nerves, as in the European forms, Rana esculenla* and Bufo 

 variabilis.^ The first nine pairs, as usual pass through the 

 intervertebral foramina, and the tenth pair through the canalis 

 coccygeus in the urostyle. Occasionally in Hyla aurea there is 

 found an eleventh nerve on each side, which, like the tenth to 

 which it is posterior, passes out by a foramen in the urostyle. 



As in the Anura generally, there is no representative of the 

 first spinal nerve or sub-occipital, shown by Furbringer to be 

 present in the Urodeles, where it passes out between the skull 

 and first vertebra ; and in Pipa dorsigera, among the Anura, 

 there piercing the first vertebra. 



Nerve II., the Hypoglossal, is somewhat thin, and passes out 

 between vertebrae I. and II. It then runs in a straight line 



* Ecker : Anatomy of the Frog (English Translation, Haslam), p. 175. 

 + Adolphi: Morphologisches Jahrbuch, 1893, p. 316. 



