THE ACT OF STRIKING 



251 



Geographical Distribution. 



Asia. — Elapin^: Naja tripudians, N. samarensis, N. bungarus ; Bungarus 

 fasciatus, B. candidus, B. ceylonicus ; Hemihungarus, Callophis, Doliophis. 



Hydrophin^: Enhydrina valakadien, Hydvus platurus, Enhydris curtus, 

 Hydrophis obscurus, and many others. 



ViPERiN^: Vipera berus, V. renardii, V . raddii, V. lebetina, V . russellii ; 

 Pseudocerastes persicus ; Cerastes cornutus ; Echis carinatus. 



Crotalin^: Ancistrodon halys, A. himalayanus , A. hypnale, and others; 

 La chests fiavoviridis, L. sumatvanus, L. bovneensis, etc. 



Africa. — Elapin^: Naja haje, N. flava, N. melanoleuca, N. nigricollis, N. 

 anhietcB, N. goldii ; Sepedon hcemachates ; Boulengerina stormsi ; Elapechis guen- 

 / Am, etc.; Aspidelaps scutatus, Walterinnesia cBgypiica, Dendraspis viridis, etc. 



ViPERiN^: Causus rhombeatus, etc.; Vipsra ammodytes, etc.; Bitis arietans, 

 B. cornuta, B. gabonica, B. caudalis, B. atropos, B. nasicornis, B. peringueyi, 



B. inornata ; Cerastes cornutus, Echis carinata, Atheris chlor echis, Atractaspis 

 congica, etc. 



Australia and Oceania. — Elapin^ : Ogmodon vitianus ; Glyphodon tristis ; 

 Pseudelaps niuelleri, etc.; Diemenia psammophis, etc.; Pseudechis porphyria- 

 cus, etc.; Denisonia superba, etc.; Micropechis elapoides, Hoplocephalus 

 variegatus, etc.; Tropidechis carinata; Notechis scutatus ; Brachyaspis curta ; 

 Elapognathiis minor ; Acanthophis antarciicus, Rhynchelaps australis ; Furina 

 calonota, etc. 



Hydrophin.e: Hydrus, Thalassophis, Hydrelaps, Hydrophis, Distera, Enhy- 

 dris, Enhydrina, Aipysurus ; Platurus. 



America. — Elapin^: Elaps, many species; Micropechis elapoides : Ancis- 

 trodon piscivorus, A. bilineatus, A. contortrix, Lachesis mutvis, L. lanceolatus, 

 and many others; Sistrurus miliarius, S. catsnatus, S. ravus ; Crotalus adaman- 

 teus, C. horridus, C. confluenius, C. atrox, C. oregonus, C. cerastesr C. mitchelli, 



C. terrificus, and others. 



The Act of Striking. 



~ The poison is secreted by glands, which are either modified upper 

 labial glands or a pair of glands occupying the sides of the head 

 behind the eyes, and which are the homologues of the parotid gland 

 of other animals. (An account of the structure of the glands can 

 be found in 'Spolia Zeylanica/ 1913.) The duct usually begins as 

 a receptacle which runs the whole length of the gland. This 

 receptacle is of importance, as it enables the reptile to store the 

 venom. Into this receptacle the smaller ducts of the gland open, 

 and from it the main duct runs forward just above the line of the 

 lip, to a point below the eye. . It is now bent backwards, and ends 

 on a small papilla on the anterior wall of the sheath of mucous 

 membrane, which embraces the base of the fang. 



Weir Mitchell describes a sphincter muscle of reddish appearance, 

 and composed of non-striated muscle, on the course of the duct of 

 Crotalus, but no such sphincter has been described in the other 

 snakes. 



The poison from the duct either runs along a groove on the 

 anterior surface of a long tooth called the fang, or else along a canal 

 formed by the sides of the groove meeting and coalescing by the 

 bending of the developing dentine. It should be clearly understood 

 that the venom duct does not directly communicate with the groove 

 or canal in the tooth, but ends close to it, the venom being con- 

 ducted into the groove by a fold of mucous membrane. The vipers 

 have the longest fangs, measuring nearly i inch. 



