700 MR. GEEABD W. BUTLEB ON THE [K^OV. 19, 



When, as is commonly the case, the various longitudinally disposed 

 viscera (the alimentary canal, liver, lung, and the longitudinal 

 vascular trunks) between which they run are displaced from the 

 positions they occupy in other animals, the course of these vessels is 

 correspondingly chcuitous. In fact, as the figures [PI. XL. figs. 2-9], 

 show, in passing from the vertebral column to the mid-dorsal 

 line of the liver, they frequently have to describe a semicircle to 

 pass round the mesial or left side of the larger right lung, which 

 commonly encroaches considerably on the left half of the body. 



Without very careful dissection the student may not in every 

 uniujected spirit-specimen that comes into his hands find all the 

 blood-vessels above referred to. I have not done so myself. In 

 some cases I have found them all ; in others now some series of 

 vessels, now others ; but in all the Snakes in my list I have 

 obtained sufficient evidence from the blood-vessels to make it clear 

 that the larger or only lung is the homologue of the right lung of 

 other vertebrates. 



(b) Some Memarks on Prof. Ooze's Papers on the Lungs of Snakes. 



Having thus presented what I believe to be without any shadow 

 of doubt the correct view of the matter, and pointed out a simple 

 means by which anyone may test the truth for himself, I think all 

 that remains for me to do further is to explain away the appa- 

 rently conflicting evidence of the figures in Prof. Cope's papers 

 above mentioned [(7) and (8)]. I say the conflicting evidence of 

 his figures, because in more than one place [(7) pp. 218 and 219, 

 and (8) pp. 836 and 838J Prof. Cope expresses himself so as to 

 suggest that he did not wish to commit himself to a use of the 

 terms " right " and " left " in a morphological sense, but that he 

 rather wished to designate those lungs which [in his opinion] are 

 situated more to the right or left side of the animal. But when 

 in his figures he labels the lungs E.L. and L.L. respectively, and 

 in his explanation of the plates states that these letters stand for 

 right lung and left lung, I think that the reader does carry away 

 the impression that by these he means the lungs which are the 

 homologues of the right and left lungs of other animals ; and this 

 impression will be deepened by certain passages in the papers 

 [e.g. (7) p. 223 and (8) p. 83S].' 



Now if we except Tgphlops [(7) pi. xi.], which is one of the 

 very few Snakes in which Cope will allow the " left " lung to be 

 absent or smaller than the " right," we find that Cope in all his 

 plates calls the best developed lung the " Left " lung and the 

 smaller or rudimentary one the " Right " ; and thus his figures are, 

 as they stand, decidedly misleading. 



Whde saying this I would, however, cordially acknowledge that 

 the figures appear to have been carefully and truthfully drawn 

 from the dissections, and such being the case, a comparatively brief 

 cross examination of the figures brings out the truth. 



Those who have carefully dissected this part of Snakes, and 



