1904.] CIRCULATORY SYSTEM IN THE OPHIDIA. 341 



portal trunk. In both specimens a single intercostal portal arises 

 near to the penviltimate arteiy of the series. It is plain, there- 

 fore, that there is no serious discrepancy of a i-eal character 

 between the gastric arteries in the two individuals. Whether 

 such differences as these are sexual or not I do not know. 



Between the superior and inferior mesenteric arteries lie the 

 ovarian arteries. The first seven of tlaese, of varying sizes, supply 

 the fully developed (right) ovary and oviduct. Then follow two 

 arising from the opposite side of the body, which go to the left 

 ovary ; finally, a single ai'tery is again concerned with the right 

 oviduct, after which rises the inferior mesenteric. Branches of 

 these genital arteries reach the fat-bodies ; but, so far as I can 

 make out, no special arteries supply those oi-gans. There is one 

 important rectal artery which arises shortly after the inferior 

 mesenteric. Between these two arteries arises the first of the 

 renal series, to be referred to immediately. Besides this im- 

 portant rectal artery I found five smaller vessels. The renal 

 arteries are four to the right, and three to the left kidney. 



Intercostal Portal jB7-anGhes.— These are few in number, and I 

 have only mapped them accurately in one (the female) specimen. 

 I counted five altogether, of which four belong to the first series 

 of intercostal arteries. These veins, like the ai'teries, vary as to 

 which side of the dorsal median line they enter or rather emerge 

 from the parietes. The first two emerge on the left side, the last 

 three on the right. Furthermore, these vessels diff'er among 

 themselves as to whether they pass below or above the aorta. 

 This position is in absolute correspondence with the point of 

 emergence from the parietes — that is to say, the first two veins 

 pass ventrally of the aorta, the last three dorsally. 



Zamenis gemonensis. 

 The anterior vertebral artery is much more extensive in this 

 species than in Z.Jlagelliformis. It extends more than halfway 

 along the neck before becoming lost by plunging into the parietes. 

 In this space a large number of intercostals are given off fi'om the 

 main trunk. I counted 9 in one specimen and 6 in the other ; 

 in the latter, however, the vertebral artery itself was not so 

 extensive, only reaching halfway up the neck. In both specimens 

 the right aortic arch gave oflf three or four intercostals befoie 

 uniting with its fellow to form the dorsal aorta. It must be 

 noticed that here, as in the last species, these cervical intercostals 

 enter the parietes exactly in the middle line. The intercostals 

 which arise after the junction of the aortas enter to the parietes 

 either to the left or to the right of the dorsal middle line, or they 

 are paired. The first 20 in one specimen and the first 14 in the 

 other are given off on the left side, and enter the parietes on 

 that side. The difference in number is not great — in one speci- 

 men 30, in the other 34 intercostals lie in front of the superior 

 mesenteric. There are 15 intercostals up to the end of the liver 

 in one specimen, 18 in the other. 



