532 THE VASCULAR AND RESl^IRATOEY SYSTEMS IN OPHIDIA. [May 1, 



single renal artery to each kidney, a fact quite independent of 

 the size of the kidney, is confirmed by several fresh examples. 



(5) More evidence is adduced to show that among the Boine 

 Snakes the relations of the anterior abdominal vein to the afferent 

 renal veins are those of the Lacertilia ; and it has been pointed 

 out that (in Boa constrictor) these veins may be symmetrical 

 in their origins in spite of the asymmetry of the kidneys. This 

 is, of course, a further point of likeness to (presumably) primitive 

 conditions. 



(6) In considering the relations of the more or less double 

 anterior abdominal vein of the Boidse to the same vein or veins 

 in other Sauropsida, it is (or may be) important to note that, at 

 any rate occasionally {^Boa constrictor), the left trunk is associated 

 by transverse connections with the epigastric vein, and the right 

 ti'unk only with the fat-body, and not at all with the epigastric 

 vein. 



(7) Attention is directed to the intercostal arteries of Erythro- 

 aviprus, which appears to offer an intermediate condition between 



the Boid Snakes and the Viperidse. To others it has appeared 

 that the Viperine Snakes are to be derived from the Opistho- 

 glyphous Colubrines. 



(8) The structure of the genus Corallus on the whole confirms 

 the current view that it is to be referred to the Boine section 

 of the Boidse. 



(9) The existence of rudiments, apparently functional, of the 

 tracheal lung are more numerous in the Ophidia than would be 

 inferred from a consultation of the literature of the subject. 

 Such traces have been described above in a number of species 

 where they have not been hitherto recorded. 



(10) The prevalence of at least traces of a tracheal lung in so 

 many and often not nearly related families is an argument for 

 considering that its existence is a retention — that it has not been 

 acquired separately in the several genera or families where it 

 occurs, but has rather been lost in those genera, &c., where there 

 is now no tracheal lung. 



(11) The view of Prof. Cope that the tracheal lung is a further 

 extension of the Lizard-like pocket extending beyond the entrance 

 of the bronchus, which is found in the functional lung or lungs of 

 many Snakes, cannot be correct, since this pocket coexists with 

 remains of the tracheal lung in some forms. 



(12) The structure of the lungs offers facts of detailed classi- 

 ficatory value ; but the wide prevalence of the tracheal lung or 

 remains of it does not tend to support the scheme of classification 

 set out by Prof Cope in its entirety. 



