606 DR. G. E. NICHOLLS ON THE 



is especially marked in the anterior vertebrpe of the column, 

 where the hinder end of a neural spine may extend backwards 

 upon the ensuing vertebra almost to the level of the notch 

 between its post-zygapophyses {of. text-iig. 1). Posteriorly the 

 spines become shorter, though still well developed. Thus, upon 

 the seventh vertebra the neural spine extends but little beyond 

 the posterior margin of the neural arch ; in the eighth it is 

 nearly vertical, and in the ninth the spine is slightly forwardly 

 directed, so that its apex approaches very closely to that of the 

 jjreceding vertebra. In this development of neural spines 

 B. tigrina is remaikable, for of European Anura Boulenger has 

 I'emarked : "Neural spines are absent or represented by a low 

 keel, which is much prolonged posteriorly in Discoglossus and 

 Pelohates " (op. cit, p. 38). 



The intervertebral foramina in the Indian Bull-frog are, 

 i-elatively, considerably smaller than are the corresponding 

 nerve-exits in R. te77iporaria, and the column has, therefore, not 

 at all the open-work structure which is so characteristic of our 

 European frogs. 



Moreover, the cartilaginous epiphyses found, upon the distal 

 ends of the transverse processes are particularly noticeable in 

 R. tigrina. Upon the third vertebra (cf. text-fig. 1) these ai-e 

 very large indeed, and backwardly directed, recalling strongly 

 the condition figured by Boulenger for Pelohates fuscus (op. cit. 

 fig. 75). 



The transverse processes also are, relatively, much longer than 

 are the corresjDonding structures in R, temj^oraria, but in this 

 respect the condition of R. escidenta is closer to that of the 

 Indian species. 



Apart from these generalities, there are notable differences to 

 be observed in the second, eighth, and ninth vertebrae of the two 

 species. 



In the second vertebra of R. tigrina there is developed a very 

 pronounced flange-like projection upon the anterior border of the 

 transverse process (text-fig. 1,/.). This varies somewhat in size, 

 but becomes very marked indeed in some specimens. It serves, 

 apparently, for the attachment of the Mon. intertransversarii 

 capitis, which have their insertion upon the base of the skull, 

 slightly lateral to the condyles. The complete absence of this 

 flange from the European Ranidse is doubtless to be attributed to 

 the much slighter development of these muscles in these more 

 slightly built frogs. 



In the eighth vertebra, the transverse processes are as long as, 

 and rather stouter than, the diapophyses of the three preceding- 

 vertebrae. They are peculiar, in the normal vertebral column of 

 R. tigrina, in that alone of all the transverse processes they are 

 sloped slightly forwardly {conf. Howes, '02, fig. 35, with my text- 

 fig. 1). The well-developed neui^al spine rises almost vertically. 



In the ninth vertebra, the transverse processes should be 

 described as slightly conical (with the base of the cone distal) 

 rather than as cylindrical, which latter shape is said to be 



