3G8 MR. F. E. BEDDARD OX THE [Feb. 1 G, 



Some Ge^teral Conclusioxs. 



The facts detailed in the foregoing pages permit of some general 

 conclusions as to the structure of the aiterial system in the 

 Ophidia. 



In this genei^al survey of that system I have naturally compared 

 my results with the most complete recent comprehensive survey 

 of the vascular' system in those Reptiles — that which is given 

 in Bronn's ' Thier- Reich.' I am unable from my own observa- 

 tions to substantiate all that is said in that work, though in 

 many points I can add nothing to the general statements therein 

 contained. 



In the fiist place, though this conclusion can hardly be con- 

 sidered a novelty, it is important to note the prevalence of 

 longitudinal systems which are developed in nearly all the organs 

 of the body. The various regions of the alimentary tract possess 

 longitudinally running vessels which are filled by several branches 

 of the aorta. The same is true of the livei', the fat-body, the 

 gonads, &c. This state of afiairs has not been sufficiently fully 

 emphasised in such figures of the arterial system as have been 

 published. 



The anterior vertebral artery enters the thickness of the 

 parietes at a vaiiable distance from the head, varying — that is to 

 say — according to the species, and the number of intercostal 

 branches which it gives oft' upon its course is not, as might be 

 inferred from the general account given in Bronn, three or four 

 only. These numbers do indeed occur ; but they are often 

 considerably increased. Moreover, these arteries are, as has 

 correctly been stated, always single — never paired ; and it may 

 be added that they always perforate the body- wall exactly in the 

 middle line, which is sometimes, but not always, the case with 

 the intercostal branches of the common aorta. With regard to 

 the latter, it will have been noted that they present many 

 variations. In the first place, they are more or less numerous, 

 and there is no exact correspondence between their numbers and 

 the length of the snake. They may be single or arranged in 

 pairs ; both arrangements occur in the same snake. When 

 single they may enter the parietes exactly in the middle line, as 

 is the case with the intercostal branches of the anterior vertebral 

 artery ; or they may lie to one side or to the other, in which 

 case there is an alternation in position which is now regular now 

 irregular. 



The gastric arteiies vary rather more widely than might be 

 inferred from the summary given in Bronn's ' Thier- Reich.' 

 There are as few as one in Lachesis gramineus, three in JVaicc 

 trijmdians, and as many as ten or eleven in the genus Coluber. 

 Their alternate arrangement to the right and left sides of the 

 stomach is a noteworthy point. 



The hepatic arteries are sometimes more than ten to twelve in 



