37 



It is difficult to account for such an abnormality for there appeared 

 to be no cause why a heart fully adult in most particulars should still 

 remain in its primitive embryonic unfiexed condition. 



Since the foregoing note was in the hands of the printer another 

 similar abnormality of the heart in the frog was discovered during class 

 work dissection in this college and was kindly handed to me by 

 Dr. Woodland. This specimen was also a full grown male Rana tem- 

 poraria and was normal in other respects except that the anterior ab- 

 dominal vein opened into the left sub-clavian vein. 



The heart was again in a primitive unfiexed condition forming a 

 bi-lobed structure 17 mm long, of 

 which the anterior lobe, 9 mm long, 

 was the ventricle and the posterior 

 was the two auricles. It was situ- 

 ated in the median line and was 

 apparently not attached in any 

 way to the surrounding tissues. 

 As the auricles were approxima- 

 tely in a normal position the ven- 

 tricle was displaced anteriorly and 

 so came to lie between the hyoid 

 bone and the muscles of the throat. 

 The sinus venosus, into which open 

 the three venae cavae, opens into 

 the right auricle and is marked off 

 from it much more distinctly than 

 in the preceding case. The two 

 pulmonary veins open into the left 

 auricle in the usual manner. The 



arrangement of the arteries is the Fig-. 3. Diagram of the heart and main 



., . ' . vessels in specimen 2. J. ^., Anterior Ab- 



same as m the previous specimen, dominai Vein; F., Femoral. Vein; Pc, 



so also is the crossing of the arte- Pelvie Vein; R., Renal Vein; Sc, Sciatic 



• IT , ij^i 1 Vein. Other letters as before. 



rial and venous systems although 



this is not quite so marked. 



Dissection failed to reveal any further abnormalities in the arran- 

 gement of the valves between auricles and ventricle or in the truncus 

 arteriosus (fig. 3). 



I have not been able to find any other records of a similar abnor- 

 mality in the frog's heart and so the foregoing cases are probably uni- 

 que or at any rate of rare occurrence. 



There is also in this second specimen another abnormality in the 

 venous system. The anterior abdominal vein, although formed in the 



