1893.J TEETJEBRAL A^fD LIMB-SKELETOIf OF THE AMPHIBIA. 271 



is liable at aU approximate in interest to that of the occasional 

 appearance of transverse processes on the first vertebra ; but, 

 with the exception of a casual mention of a case in Eatui 

 esculenta by A. Gr. Bourne \ it has remained unnoticed. His 

 specimen was very abnormal in other respects ; but I am in 

 possession of two backbones of the same species in which, while 

 the last eight vertebrae were perfectly normal, the first one or 

 " atlas " bore transverse processes, and, in addition (fig. 4 6), a 

 pair of lateral perforations (/i of figs. Ah, 10, & 11) "disposed 

 serially with the intervertebral foramina. These specimens reached 

 me in the dried state ; but careful examination of the remains of 

 the soft parts which lay about one of them revealed the presence 

 of nerve-fibres within one of the perforations in question, and 

 thus proved it to have transmitted a nerve. 



On seeking for further hght upon this variation, I have dis- 

 sected certain of the larger Eanoids ^ in vain ; but my friend 

 Prof. Chas. Stewart, of the Eoyal College of Surgeons, has called 

 my attention to the existence of the nerve-exits in the only 

 specimens of Buna catesbiana and B. macrodon which his Museum 

 possesses (c/. figs. 5 6 & 9, & 3 & 8), and of powerful transverse 

 processes in the first species named. Strangely enough, neither the 

 skeletons in the Natural History Museum, nor the carcases of 

 these species therein preserved wliich I have had the opportunity 

 of dissecting ^ re\eal the remotest traces of either the one or the 

 other. 



Hyrtl called attention twenty-eight years ago, in his celebrated 

 Monograph on the Japanese Salamander (J/et/aZoiftiracAits [^Crypto- 

 hranchus] jajionicus), to the existence of a spinal nerve which per- 

 forated the arch of the " atlas ; " and Humphry, six years later, 

 described the nerve more fully ^ as the " sub-occipital," tracing it 

 to a distribution to the " foremost portion of the sub-vertebral 

 rectus "muscle. Fischer had (in 1864) ah-eady described a similar 

 nerve' in MenohrancJius, believing it to be peculiar to that animal 

 among Frodeles; and it is interesting to note that he traced it 

 to a distribution in the "occipitalis minor" muscle. Hyrtl, in 

 accordance with the facts of the case, was led to regard the so- 

 called " atlas " of the Amphibia as a product of fusion of the " atlas 

 and epistropheus " of the higher Tertebrata ; but this revolutionary 

 conception has been almost lost sight of, except for its acceptation by 

 Hoffmann' and so far as the work of Albrechf and Stcihr', alluded 

 to below, may bear upon it. Neither it nor any facts concerning 



^ Quart. Joiirn. Micr. Sci. vol. xxiy. p. 86. 



^ Calt/ptocepkalus ffrat/i, Leptodactylus 'pentadaetylus, and Rana guppyi. 

 ^ For permission to do this my best thanks are tendered to Dr. A. Giinther, 

 F.K.S., and my friend Mr. G. A. Boidenger. 



* Journ. Anat. & Phys. vol. vi. p. 48 (1870). 



^ ' Anat. Abhandlg. ii. d. Perennibranchiaten und Derotremen,' Hft. i. p. 158 

 (Hamburg, 1864). 



^ Bronn's Thier-Eeich, Bd. vi. p. 54. 

 ■ Zool. Anz. 1880, p. 477. 



* Zeitschr. f. wiss. Zool. Bd. xxxiii. p. 477, and Bd. xxs\i. p. 68. 



19* 



