340 ME. F. E. BEDDAKD OX THE [Feb. IG, 



specimen. In this, however, the first 11 intercostals pierced the 

 body-wall to the left of the middle line, after which the alternate 

 and occasionally paired arrangement began. The greater distance 

 from each othei- of the anteiior set of intercostals, and the fact 

 that they enter the body on the left side, seem to be distinctive 

 features in this Snake, as in some others. 



Visceral branches of the Common Aorta. — For the first pai't af 

 its course the aorta gives oflf a considerable number of minute 

 branches to the oesophagus and to the liver. Passing backwards 

 these gradually grow in importance. They repeatedly branch, the 

 branches become fused so that one may almost speak of a longi- 

 tudinal system running in the mesentery attached to the liver. 

 The first of the particulai'ly strong bi-anches arises opposite to the 

 eighth of the intercostal branches of the aorta, and also opposite 

 to the posterior end of the liver. The vessel differs from the pre- 

 ceding ones in the fact that it supplies the walls of the alimentary 

 .tract and only sends a small branch to the liver, and also appa- 

 rently to the walls of the large blood-vessels entering the liver ; it 

 is thus, so to speak, the fii'st of a new series of branches. The next 

 of these vessels aiises 32 mm. further on ; it appears to supply 

 the stomach exclusively. The method in which its twigs are 

 distributed to the stomach is as follows : — The vessel when it has 

 reached the stomach immediately bends backwards and runs along 

 the stomach, becoming continuous with the next visceral branch 

 of the aorta. Side branchlets are given off fi'om this connnon 

 longitudinal trunk. The next visceral vessel arises just opposite 

 to the gall-bladder ; Avhen it has arrived at the stomach it divides 

 into three branches. One of these has been already referi-ed to 

 as joining, or rather as in ending in, the previous gastric branch 

 of the aorta; the second branch runs along the surface of the 

 stomach on the opposite side, while the third and shoi'test branch 

 supplies at least the gall-bladder. The next branch, the supei'ior 

 mesenteric, arises from the aorta 28 mm. beyond the origin of 

 the gasti-o-splenic. It runs to the stomach in close connection 

 with a vessel from the parietes to the portal vein. Just before 

 reaching the stomadi this artery divides into two bi-anches which 

 run in the same straight line ; but one is directed forwards, the 

 other backwards along the surface of the gut ; the latter runs 

 along the intestine in close association with the portal vein, gives 

 off branches, and finally returns to the aorta, being continuous 

 Avith the inferior mesenteric artery. 



In a second specimen (a male) the gastric ai-teries are a little 

 different — superficially, at any rate, if not essentially. The last 

 artery occupies precisely the same position, reaching the gut just 

 at the gall-bladder. Although the snake is a rather smaller one, 

 the interval between the gall-bladder and the end of the liver is 

 greater than in the larger snake, about 5 inches to 4 inches. 

 Cori-esponding to this is a larger number of gastric arteiies lying 

 behind the liver. I counted six of them. Each is, with the ex- 

 ception of the third and the sixth, accompanied by an intercostal 



