940 MR. F. E. BEDDARD ON THE ANATOMY [DeC. 14, 



difl'erences, and this West African Monkey differs more from 

 Cehus and Fithecia than are those two genera from each other. 

 The intercostal series (text-fig. 294 0) are single arteries in their 

 origin, and only divide later to form the two intercostals of the two 

 sides of the body. The first two arteries of the series are closer 

 together than those which succeed, and I ascertained that they ai'e 

 bronchial arteries, for I succeeded in tracing them into the tissue 

 of the lung. As I have already mentioned, the condition of 

 these arteries furnishes another argument in favour of regarding 

 the whole series of arteries as forming morphologically one series. 

 For each of these first two arteries was fully as large an artery as 

 the intercostals proper. The artery in each case continued for 

 some distance of the same calibre and then suddenly diminished 

 in calibre to a slender twig running to the lung tissue. It looks 

 indeed as if at the point of sudden diminution in calibre there 

 was originally an intercostal arising here which has become 

 aborted. And this seems to be the most probable explanation of 

 the anatomical fact which is illustrated in the accompanying 

 figure (text-fig. 294 C, a). The number of intercostals in this animal 

 was nine after the two bronchials already referred to. All of 

 these followed each other at approximately equivalent intervals. 

 The first five were jjrovided with a small arteriole to the right 

 side, which I do not regard as a small additional intercostal, but 

 as an oesophageal artery. After the ninth intercostal there was 

 a considerable vacant space, and then just in front of the large 

 visceral trunks a single pair of intercostals ; in this region, there- 

 fore, alone are the intercostals paired trunks. 



I fancy that the Primates generally will prove to possess 

 invariably a right azygos only; though, indeed, materials for 

 forming an opinion U230n this point do not exist to any great 

 extent. My own experience, however, points in that direction ; 

 and in any case Pithecia jnthecia has an azygos upon the right 

 side only which gives off nine branches. Of these the second, 

 which is correspondingly bifurcate, supplies two intercostal spaces. 

 I have a note by Mr. Forbes as to the azygos of Fithecia albinasa 

 which he describes as " trifid," meaning, I take it, that the 

 anterior two branches are of equal calibre with the main longi- 

 tudinally running trunk. 



Although I found the kidneys to be pretty well symmetrical, 

 the left renal vein flowed into the postcaval at a point a little 

 above the right renal vein — a converse asymmetry being the 

 rule among Mammals. This state of affairs appears to agree 

 with that recorded for Fithecia monachus by Flower (5, p. 332), 

 who remarks that the right kidney is placed slightly lower than 

 the left. On the other hand Forbes records the converse con- 

 ditions in Fithecia albinasa. As in other Primates, the right 

 sjiermatic vein flows into the postcaA"al a little below the right 

 renal, while the left spermatic enters the left renal. I may take 

 this opportunity of stating that in Colobus guereza the spermatic 

 and renal veins were precisely as in Fithecia pithecia. 



