1910.] ANATOMY OF HIPPOPOTAMUS AMPHIBIUS. 229 



opened into the heart by a narrow canal, while the precaval 

 opened " par un sinus enorme." 



Dr. Chapman found in two Hippopotami, about five and a 

 half feet long, that the precaval was " very large and readily 

 transmitting blood to the heart, whereas the inferior cava, at least 

 that part above the diaphragm, is rather small." 



Dr. Orisp's statements are a little uncertain in their inter- 

 pretation. He wrote that the " superior cava ... is short, thin, 

 and very capacious, measuring 1 1 inch in diameter. The inferior 

 cava is also very capacious." The latter phrase might, however, 

 refer to the postcaval below the diaphragm ; otherwise it is 

 obviously in direct contradiction to Chapman. In any case the 

 specimen at the College of Surgeons Museum can be examined, 

 and it will, I think, be found that my statement concerning it is 

 correct. 



The coronary arteries are very large. It is important, however, 

 to mention that (as my colleague, Dr. Plimmer, points out to 

 me) this is associated with degenerative changes in the muscle of 

 the heart and mucoid degeneration of the visceral layer of the 

 pericardium. Still a large size of these arteries seems to be found 

 in other aquatic Mammalia *. They are not dealt with by 

 Gratiolet f. In the heart examined by myself the arteries were 

 two, arising on opposite sides of the aorta. The two coronary 

 arteries differ in their size and distribution. That which is 

 concerned with the blood-supply of the right ventricle is much 

 the larger. This coronary passes with a sinuous course along the 

 anterior erlge of the ventricle, between it and the auricle. At 

 the end of the right ventricle the artery bends downwards and 

 runs along the inter-ventricular border, but as two arteries, for 

 it divides near to the point of alteration of direction. Before 

 this the branches of the coronary are inconspicuous. 



The lesser coronary artery supplies the walls of the left 

 ventricle. It passes straight from the aorta to the commence- 

 ment of the ventricle ; here it bifurcates into two arteries, of 

 which the shorter (that which is to the right when the heart is 

 viewed from the side of the left ventricle) runs down towards the 

 apex of the ventricle along the border line of the left and right 

 ventricles. The other branch runs similarly along the base of 

 the left ventricle to the other side of the left ventricle, when it 

 suddenly changes its direction and runs towards the apex of the 

 heart, but at a considerable distance from the neighbouring 

 branch of the other coronary artery. It does not reach the apex, 

 at least not as so important a branch. It is evident from their 

 course and relative importance that these arteries in Hippo- 

 potamus hardly differ from the coronary arteries of man. 



Among the arteries dealt with by Gratiolet we do not find any 

 account of the inter costals. These I have represented in the 



* Cf. Beddard, " Notes upon the Anatomy of a Manatee {Manatus munguis)" 

 P. Z. S. 1897, p. 52. 

 t L»c. cif. p. 361. 



