1895.] IilTNGS OF Sll'AKES, AMPHISB^l^ID^, ETC. 699 



of larger branched vessels, and running as they do in a dorso- 

 ventral direction they, so to speak, constitute a double or treble 

 palisade between the two lungs [or to the left or right of the one 

 lung which may be present]. 



Thns, firstly, the aorta gives off dorsalvvards a whole series of 

 vertebro-intercostal arteries to the vertebral column and adjoining 

 body-wall, and ventralwards arteries to tfie oesophagus and 

 stomach, while from these a series of veins passes to the portal 

 system of the liver. With the exception of a few Amphisbaenidae, 

 in which all or part of the last-mentioned veins run in the right 

 dorsal hepatic Ugament \ all the above-mentioned blood-vessels run 

 in the median septum ; and it will be seen that they form a well- 

 marked palisade of vessels across the space between the mid-dorsal 

 line of the liver and the vertebral column. 



Secondly, starting from the aorta, we have arteries passing direct 

 to the liver. 



Thirdly, in a number of elongated snake-like Lizards [as was, I 

 believe, first described for Lizards by Hochstetter '^ in Anguis and 

 Pseudopus (Ophisaurus)'] we find that the main part of the vertebro- 

 intercostal blood of the hepatic region of the trunk is returned by 

 a series of veins that run from the dorsal body-wall to the liver 

 via its right dorsal ligament '. 



Now we find all of these above-mentioned series of blood-vessels 

 fully developed in Snakes throughout the entire liver-region, as 

 was admirably described by Schlemm'' as early as 1826 ; and they 

 show us that the larger, or only functional, lung of Snakes is the 

 right lung. 



^ E.g. in Amphisbcsna and Lepidosternon most or all of the veins from the 

 oesophagus and anterior part of stomach rim in the right ligament, which of 

 course in these cases joins the alimentary canal. In Blanus cinereus part of 

 the veins run in the right and part in the median ligament ; while in the 

 " Emphyodont" Pachycalamus and Trogonophis the veins run, as is, so far as I 

 am aware, the rule for all other vertebrates, in the median membrane. 



^ F. Hochstetter, " Beitrage zur Entwicklungsgeschichte des Venensys- 

 tems der Amnioten. II. ReptiUen," Morph. Jahrb. Bd. xix. Heft 3, pp. 428- 

 501, pis. xv.-xvii., Dec. 1892. 



* I find these veins running in the right dorsal ligament of the liver in 

 Scelotes, Lygosoma, Lialis, and various Amphisbmiiida, e. g. Amphishcena, Lepido- 

 sternon, Pachycalamus, and they doubtless occur in the other snake-like Lizards 

 examined. There may be as many as five, as in Amphisbmna, and perhaps 

 more, spaced throughout the whole length of the liver. 



A well-marked series of corresponding vessels is seen in Amphiuma and also 

 in Ickthyopkis, though in the last case they do not spring so directly from the 

 vertebral column, but arise, as Hochstetter says has been described by Semon, 

 from the unpaired vein between the mesonephric excretory organs which comes 

 to take the place of the posterior cardinals of that region. 



* Fried. Schlemm, " Anatomische Beschreibung des Blutgefassystems 

 der Schlangen," Zeitsehrift fiir Physiologic (Ed. G. R. & L. Ch. Trevirauus), 

 Bd. ii. pp. 101-124, pi. vii. (Darmstadt, 1826). See especially pp. 11.5, 121 & 

 122. On p. 121 he notices the series of vertebro-intercostal veins flowing into 

 the portal vein in the Hver, which were so commonly omitted in the descriptions 

 published between 1826 and Hochstetter's paper of 1892, while curiously the 

 comparatively insignificant, but, if I may so say, orthodox, vein that brings 

 back blood from the first few postcardiac segments was always duly noticed. 



