1908.] 



ANATOMY OP A FROG. 



25 



BreiHceps are obviously part of the same muscle, most of whose 

 fibres have an oblique direction. But elsewhere the rectus ab- 

 dominis is obviously external to the obliquus internus. It would 

 seem, in fact, impossible to go further than to declare the two 

 layers of the abdominal musculature homologous with the two 

 layers in other Batrachians. Aw exact homology between indi- 

 vidual muscles derived from these layers would seem to be 

 impossible of assertion. It is quite remarkable to note what 

 great differences in the disposition of the fibres in these two 

 layers can exist between closely allied Batrachians, and how 

 plastic these structures prove to be as conti'asted with many 

 others whose functions would also seem to be involved with the 

 peculiar mode of life of this frog. 



§ Muscles of the Thigh. 



The muscles visible on the superficial aspect of the thigh are 

 shown incidentally in the figui-e (text-fig. 3) representing a 

 general view of the musculature of Brevicejys, and in a more 



^c^.m^r 





Muscles of the inside of the thigh of JBreuiceps. 



a. Skin-muscle referred to in text. ^cic^.Sr. Adductor brevis (or magnus?). Add.L. 

 Adductor longus. Add.m. Insertion on to knee of one of adductors, perhaps 

 comparable to the adductor magnus of other Frogs. R.i.maj. Rectus internus 

 major. R.i.min. Rectus internus minor. V.i. Vastus internus. x. A separate 

 adductor slip. 



elaborate way in the accompanying figure (text-fig. 6), which 

 represents the thigh-muscles more highly magnified. I take as 



