CROCODILIANS, LIZARDS, AND SNAKES. 7 IS' 



These experiments have again aroused tlie interest in the morphology and physi- 

 ology of these glands, and two years ago, sixty years after Duvernoy's work, Mr. F.. 

 Niemann i)nblished ' some investigations upon this subject. Among other snakes he' 

 dissected and described two species with i)osterior grooved fangs, and he clearly 

 demonstrates that, in both, the yellowish gland has already passed the innocuous 

 stage and become a true poison gland, though structurally somewhat intermediate — 

 as are, iu fact, the fangs. He found in both species the yellowish gland well cir- 

 (■umscribed and clearly differentiated from the true supralabial gland, although 

 both glands are contained in the same envelope of connective tissue, and he was 

 able to trace the single duct leading from the yellowish gland to the groove of the 

 posterior elongated fang. One of the species was Tragops prasinus, Wagler (the 

 same species with which Professor Vaillant experimented), and an inhabitant of the 

 East Indies, the other being Sihon annulatum (Linnaeus), from tropical America. 

 Fig. 1 is a copy of Mr. Niemann's schematic representation of the arrangement in the 

 former. Fig. 2 shows a section of the grooved fang near its base, copied from the 

 same author. 



That these snakes are not entirely harmless, even to man, is evident from the very 

 recent experience of Mr. J. J. Quelch, of Georgetown, British Guiana,- who was, 

 bitten on the first finger by a large specimen of the common red-white-aud-black- 

 banded snake, Erythrolamprus venustissimus, driving its hinder grooved teeth three 

 times down into the fiesh. About half an hour after, the finger became much swollen 

 at the place and distinctly very painful. It was not till about four hours afterward 

 that real relief was obtained, though the place was tender for a much longer time. 

 Another case was that of the clerk iu the Museum, who was bitten on the finger by 

 a young specimen of the common frog snake, or Mattipi, Xenodon severus, whose 

 hinder enlarged teeth were driven deeply into the flesh, with a result similar to that 

 described iu the case of the other snake. 



It will l)e observed that while the snake by which Mr. Quelch himself was bitten; 

 is a true opistoglyph with grooved posterior fangs, the one which caused a similar 

 result in the clerk, viz, the Xenodon, has the enlarged posterior teeth solid and not 

 grooved. I would call attention to the fact, however, that this identical species is; 

 described by Duvernoy'^ as having the yellowish gland well diff'erentiated. That 

 the bite of the allied species, Xenodon rhahdocephahis, did apparently have no unpleas- 

 ant effect on Dr. Stradling^ is not difficult of explanation in view of the fact that, 

 occasionally the bite of some of even the most dangerous snakes has been ineftect- 

 ive; but enough is said to show that the question is not an unreasonable one: Is it^ 

 essential for a truly venomous snake to possess f/rooved fangs? 



As a matter of fact, at the very moment of this sentence going to press, the ques- 

 tion seems answered conclusively in the negative by the experiments of I'hisalis: 

 and Bertrand, who have shown that the saliva of even ordinary solid-toothed harm- 

 less snakes contains the same specific poison which characterizes the dreaded! 

 Thanatophidia. 



But four geuera of Opisthoglj^pba enter the political bouudaries of 

 the United States, namely, Sibon, Trimorphodon, Goniophanes, and 

 Tantilla. Of these only the second and fourth can be properly reckoned 

 to the Oolunibiaii Fauna. 



Snakes are popularly believed to possess a power of "charming" or 

 attracting to themselves other animals, especially birds, against their 

 will, so that they easil^^ capture them for food. This belief rests on a 

 habit which is usual among the smaller birds, of annoying other ani- 



• Archiv f. Naturgeschiohte, LVIII, Pt. 1, 1892, pp. 262-286, pi. xiv, 



-Zoologist (3), XVII, .January, 1893, pp. 30.31. 



^^ Ann. Sci. Nat., XX.\, 1833, pp. 14, 15. 



••Referred to in Miss C. C. Hopley's "Snakes, etc.," 1882, p. 400. 



