1908.J BATRACHIAN RHINODERMA DARWINI. 693 



between the two last-named muscles is greaterthan it is represented 

 to be in liana. The fig'ure of Rhinoderma (text-fig. 1 49) shows that 

 in that frog the vastus is moi'e than twice the breadth of the semi- 

 membi'anous. The rectus anticus of Rhinoderma is peculiar in 

 that it is a very small and slender muscle covered at its origin 

 from the ilium by just the front end of the glutseus. It is thus 

 an inappreciable portion of the triceps fetnoris complex. The 

 biceps femoris is much hidden by the vastus externus and semi- 

 membranosus, between which it lies. Indeed it is only visible for 

 a very short distance at its insertion. Ixi this the genus agrees 

 with Breviceps. 



The semitendinosus is not shown in the two figures (text-figs. 148, 

 149), which illustrate the musculature of the thigh, since it is 

 completely hidden on the inner aspect of the thigh by the rectus 

 internus major. "When the latter is cut through and reflected the 

 semitendinosus is brought into view. It is formed by the union 

 of two heads as in Rana ; but these do not unite until more than 

 halfway down the thigh. They are moreover fleshy through- 

 out and roughly speaking of equal size. One head arises, as the 

 thigh is seen dissected from the ventral aspect, superficially to the 

 other. It arises from the symphysis pubis in close apposition to 

 the great adductor and the two recti abdoiaiinis. The second head 

 is better shown when the first head is cut through and reflected, 

 since it is distinctly deep of it. It is then seen to run back to 

 its origin in close apposition to the rectus internus major and to 

 arise from the pubis very close to it. I observed no tendinous 

 origin of this head, and no such connection with its head as is 

 figured and described in the Common Frog. 



§ Resume of facts and Systematic Position of Rhinoderma. 



As might be expected from their vevy different way of life, the 

 genus Rhinoderma presents, as we have seen, numerous anatomical 

 difierences from its ally Brevice2:)S. Several of these are already 

 known, and are described in such works as Mr. Boulenger's 

 ' Catalogue of the Batrachia Salientia,' and in Dr. Gadow's treatise 

 on Amphibia and Reptiles in the ' Cambridge Natural History.' 

 I leave aside in the present enumeration those external aiad osteo- 

 logical features which are dealt with in those and other works. 

 A general survey of the structure of the muscles shows plainly that 

 Breviceps has departed much further from the more usual sti'ucture 

 of the Batrachia Salientia than has Rhhioderma. And this state- 

 ment applies also to the viscera. The extraordinarily enlarged 

 posterior Ij-mph-hearts of Brevicep)s are not found in Rhinoderma ; 

 the liver of the latter has the more normal form of that of Rana, 

 It is, however, in the musculature that the most numerous 

 divergences between the two types are to be met with. The 

 remarkable specialisation of the obliquus muscles, which I have 

 desc];ibed in detail in Breviceps^ does not occur at all in Rhino- 

 derma, which is broadly speaking like Rana in this respect. 



