1907.] OF A FROG OF THE GENUS MEGALOPHRYS. 345 



upon the anatomy of the Frog*. In this figure the muscle is 

 seen when the frog is examined as lying upon the dorsal surface 

 to rise gi-adually fi-om the musculai- parietes and to end upon the 

 cesophagus near to its dorsal side. It is a strap-shaped, qiiite flat 

 band of muscle. 



In Rana tigrina, where I have examined the muscle carefully, 

 and which is a larger species arid thus lends itself more success- 

 fully to such an examination, the muscle is very obvious and 

 precisely as in R. esculenta. Its fibres can easily be seen to end 

 vipon the oesophagus. I could not, however, detect the fact — if it 

 be a fact — that some of these fibres cross the oesophagus to be 

 inserted upon the dorsal face of the lung (or rather, of course, its 

 peritoneal sheath). On the other hand, a portion of the muscle 

 in cjuestion is inserted uj)on the cervical aponeurosis, which lies 

 in front of the lungs and heart and shuts ofl' the neck from the 

 trunk. These muscle-fibres pass into the aponeurosis, and may 

 well be attached to the lung ventrally, since they appear to reach 

 the pericardium beyond it. 



. The large Rana guppyi shows an interesting deviation from 

 these diaphi-agmatic structures in Rana tigrina, which I do not 

 think is entirely a matter of greater clearness of visibility owing 

 to its much larger size. It is, as I believe, to be put down rather 

 to the greater complexity in the detailed structure of animals of a 

 large size as compared with their smaller allies. In this Frog the 

 transversalis muscle is precisely as in Rana tigrina, save for the 

 fact that two considerable bands of fibres at no great distance 

 from each other raise themselves from the common mass of the 

 transversalis and pass just under the oviduct to the aponeurosis of 

 the lung. It seems to me to be plain that these detached slips 

 correspond to that portion of the corresponding muscle (with a 

 different origin however) which in Pipa and Xenopus are very 

 conspicuously attached to the lung, as is shown in the figures of 

 Dr. Keith t and myself t. Except in size and importance there 

 is thus less difi'erence between Rana (at any rate so far as concei-ns 

 R. guppyi^ and Xenopus and Pipta as regards the insertion of the 

 "spinal segment of the diaphragm" than might have been 

 inferred. As has been pointed out by Dr. Keith, the dorsal part 

 of the " diaphragm " in Xenopus has migrated back § — so at least 

 it would seem — to the ilium from wdiich it arises, arid in Pijja 

 further back still, i. e. to the femur, whence the muscle in question 

 springs in that genus. I have, however, now to record some new 

 facts which tend to throw a doubt upon this interpretation of 

 Dr. Keith. 



In Megalophrys the transversalis sheet to the oesophagus is a- 

 muscle of very great extent ; it is, for instance, fully twice the 

 length (not relatively, but actually) of the same muscle in Rana 



* ' Anatomie des Frosclie.i,' by Gaiipp. 



t Loc. cit. fig. 10, p. 254, & fiV. 11, p. 255. 



X Loc. cit. fig. 1, p. 842. 



§ These facts weve also correctly noted by myself. 



