362 MK. F. E. BEBDxVRD OX THE [Feb. 16, 



conditions observable in the spermatic arteries. The anterior 

 kidney has but two arteries, of which the first arises in front of 

 the first renal artery of the posterior kidney. The second artery 

 of the anterior kidney arises exactly opposite to the fourth renal 

 artery of the opposite kidney. The posterior kidney has six 

 arteries, which, with the exception of the first, lie between the 

 inferior mesenteric and the ensuing intestinal artery. There is 

 finally an arteiy to each ureter, of which that to the posterior 

 kidney lies after the fourth intestinal artery. 



Python spilotes. 



In this Snake the anterior vertebral artery is of much less 

 calibre than the right aortic arch, of which it is obviously a 

 branch, and not, as in Zamenis Jlagelliformis (see p. 338), prac- 

 tically its main continuation. It runs up very close to the head 

 before becoming imbedded in the body- walls. It disappears from 

 view only 3 inches behind the tip of the snout. Its branches 

 are regularly intervertebral, and therefore numerous ; the most 

 striking difierence which the arteiy in this snake shows from that 

 of Zamenis and many other snakes, is the fact of the existence 

 of a branch which may be termed the posterior vertebral artery. 

 This is the first branch of the vertebi-al artery, and is given off 

 immediately after the origin of the latter from the aortic trunk 

 at a distance of 1 cm. from the aortic ai'ch ; it has therefore very 

 nearly a separate origin from the aorta,. This trunk passes back 

 along the middle line of the body, closely apposed to the parietes; 

 it receives on the one hand the intercostal arteries which arise 

 from the aorta and gives olf, on the other, a series of branches 

 which run to light and left and which are, I take it, the equiva- 

 lents to the branches of the intercostals in many other snakes * 

 which run also right and left. The existence of this superficial 

 posterior vertebral artery is a further extension of the longi- 

 tudinal system of trunks which is so characteristic of the Ophidiat. 

 This longitudinal arteiy is not, however, limited to the " thoracic " 

 region ; with interruptions it continues considerably farther. 

 The superficial artery ends at a point just about opposite to the 

 commencement of the liver, during which space (of 7 or 8 inches) 

 only two arteries from the aorta reach it. After this point and 

 from it to the end of the liver I counted seven intercostal arteries 

 arising from the aorta. Each of these on arriving near to the 

 dorsal middle line of the body divides and runs forwards and 

 backwards as a superficial vertebral artery, giving ofi" paired 

 branches as usual which penetrate the parietes ; the successive 

 superficial arteries are so ai-ranged with reference to each other 

 that they leave no vertebra unsupplied — that is to say, one com- 

 mences immediately after the end of another. A. variable number 



* Hopkinson & Pancoats {loc. cit.) do not figure intercostals at all, and Jacqiiart 

 does not represent tlie secondarj' connections as occurring in the species examined 

 by him. 



t jF. g.j Hamadryad on p. 353. 



