1908.] OF THE BATRACHIAN GENUS HEMLSUS. 931 



in Xenopus are more primitive than those found by the above 

 writers to occur in Rana. The hearts are larger and, extending 

 as they do over a larger area of the body, are more widely 

 separated, and thus more completely distinct than can be the 

 case with Rana, when so small a cleft contains the three hearts — 

 or the trifid hearfc, — which are not indeed difficult to overlook 

 altogether. Whatever may be the case with Rana esculenta, I 

 found in a specimen of Rana guppyl a single lymph-heart on each 

 side posteriorly, and measuring about 6 mm. in length ; it lay in 

 quite the usual position in front of the pyriformis muscle, but 

 well behind the glutseus, sejjarated from it, in fact, by the posterior 

 end of the ilium. 



The direction of the heart is rather obliquely outwards, very 

 nearly parallel to the pyriformis muscle. Although each heart may 

 be accurately described as a single heart, the cavity is completely 

 divided across its major length (i. e. transversely to the long axis 

 of the pyriformis muscle) by a septum of the same appearance 

 and texture as the general parietes of this lymph-heart into 

 two quite separate chambers. This division, however, is merely 

 a septum ; there is no question of any separation of the obviously 

 single heart into two hearts. Nor is there any external constric- 

 tion of a marked character which could fairly justify a statement 

 that there were two consecutive lymph-hearts present on each side. 

 I may say that the lymph-hearts on both sides of the body of 

 this Frog were identical. This, it may be observed, is a very 

 difierent condition of the postei-ior lymph-heart to that which 

 has just been described in XenojnijS. In the latter genus, I i-epeat, 

 there are three distinct lymph-hearts on each side, in Rana guppyi 

 only a single heart the cavity of which is divided *. 



I may take this opportunity of calling attention to the anterior 

 lymph-heai't in Rana guppyi, where it is very conspicuous on 

 account of its large size. It is quite 9 mm. long (when slightly 

 stretched perhaps) and lies in a lymph-sac completely covered by 

 the suprascapula, which has to be lifted up in order to display it. 

 The sac and the contained heart are bounded by the longissimus 

 dorsi and the retrahens sca,pulfe on the inside, and by the trans- 

 verso-scapularis tertius on the outside t- The greater part of 

 the Ijaiiph-heart consists of a single chamber, in which there is 

 no trace of any septa. At the inner side, however, an incomplete 

 septum partly separates off a very small chamber, which is about 

 1-5 mm. in breadth. This contains, I believe, the oi^ifice into the 

 vein. It would be better perhaps to describe the incomplete 

 septum as a valvular flap which regulates the flow of blood and 

 lymph. In any case, there is no complete division of this anterior 

 lymph-heart into two chambers, such as has been described in 

 the posterior lymph-hearts of the same Frog. 



* Mr. Bui-ne kindly allows me to quote a letter in which he informs me that 

 the posterior lymph-hearts in a specimen of this Frog in the College of Surgeons 

 Museum are quite similar. 



f For these muscles, i'. supra. 



