938 



MR. F. E, BEDDARD ON THE ANATOMY 



[Dec. 14, 



them in any particular type witii a view of gathei-ing material 

 for a future generalisation. In Pithecia pitliecia the arteries in 

 question arise from the aorta by paired orifices, as is shown in 

 the accompanying figure (text-fig. 294 A). In previous descrip- 

 tions of the intercostal arteries of a few mammals, I have 

 described the whole series of arteries which arise from the aorta 

 on the dorsal surface behind the origin of the great vessels of the 

 neck and in front of the coeliac and renal arteries. These arteries 

 undoubtedly form a morphological series, though one or two 

 of the more anterior really are bronchial arteries, being the 

 nutritive arteries of the lungs. It is, however, impossible to 



Text-fig. 293. 



^"X.. 



Interior of right ventricle of Pithecia pithecia. 



A & D. Papillary muscles of septal lialf of valve. 

 B & C. Papillary muscles of outer flap of valve. 



draw a hard and fast line between such arteries as are distributed 

 to the lungs and those which supply the dorsal parietes and are 

 thus more accurately to be termed intercostals. For some of the 

 arterioles which go to the lung tissue arise from intercostals, 

 while others are undoubtedly independent. A further proof of 

 the impossibility of absolutely distinguishing the two is to be 

 seen in the case of Colohus guereza, the intercostals of which 

 will be described later ; and I refer to the ensuing description of 

 the arteries of that species. Taking this view, the first three 



