1909.] 



OF MONKEYS OF THE GENUS PITHECIA. 



939 



arteries of the series now under consideration in Pithecia pithecia 

 form a triangle with the apex pointing to the right, then follow 

 six pairs of arteries, the orifices of which are rather obliquely 

 set with reference to each other and which are rather wide apart. 

 Thereafter the intercostal arteries are more symmetrical and 

 perhaps closer together. 



Text-fig. 294. 



^ i 



A 



B 



The coinmencing aorta of several Monkeys cut open to expose the origins and 

 arrangement of tlie intercostal arteries, for an explanation of whicli see text. 



X. Fithecia pithecia. B. Cehusfatiiellus. C. CoJohtis guereza. 



For the purpose of comparison, I have examined the cori-es- 

 ponding arteries in the New World Monkey, Gehus fatuelhbs. 

 There is a general correspondence with Fithecia, but differences 

 of detail. Thus the triangle of presumably bronchial arterioles 

 (text-fig. 294 B) is nearly the same. After this is a series of five 

 pairs of intercostals which are closer together than in Pithecia, 

 but oblique in the same fashion with the exception of the first 

 pair which are oblique in the reverse direction, the right-hand 

 artery being in advance of the left-hand artery. After this series 

 the intercostals become symmetrical, and there are four pairs of 

 these in front of the coeliac artery. An example of Colobus guereza 

 came to hand at the time that I was engaged in studying the 

 anatomy of Pithecia pithecia, and 1 have drawn up some notes 

 upon its intercostal arteries with a view of comparison on the points 

 dealt with in the present communication. Naturally there are 



