REPTILES 



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CLASSIFICATION. 



The Reptilia include two orders of importance to the tropical 

 medical officer, viz. : The Ophidia and the Lacertilia. The former 

 is all important as it contains the venomous reptiles. The Ophidia con- 

 tains two important families, viz. : The Colubrid^e and the Viperid^. 



(I) The Colubridae. 



These form nine-tenths of the order Ophidia. All snakes other 

 than pythons and vipers belong to it. There are three groups: — 



(i) Aglypha. These have solid ungrooved teeth. Their saliva is 

 toxic to rats and mice but not to man. Among them are the common 

 British snake (Tropidonatus natrix), the North American water 



Poison-gland and fangs of a venomous snake {Nafa tri- 



pudiatts, Cobibridct). (Natural size.) 



L, Lobe of the gland ; D, poison-duct ; F, fang attached 



to the maxillary bone ; G G, gland ; M, capsule of mucous 



membrane surrounding the fangs ; R, reserve fangs ; 



A A, muscular fascia covering the gland. 



(After Sir Joseph Fayrer.) 



mocassin (T. fasciatus), the Indian rat snake (Zamenis mucosus), and 

 the African egg-eating snake (Dasypeltis scabra). 



(2) Opisthoglypha. {oTTLaOev = behind; ')\v<p7] = a groove). 

 These have one or more of the hinder teeth in the upper jaw grooved. 

 As their fangs are situated at the back part of the mouth they are not 

 well developed and are not very harmful to man. Among them are 

 the Indian tree snakes (Dipsadomorphin^e), the Indian egg-eating 

 snakes and water snakes (Homalapsiuce). 



(3) Proteroglypha ( irporepu == before). — These have the front 

 upper teeth well developed and grooved anteriorly, connected with 

 ducts leading from well-developed poison glands. All are dangerous 

 to man and animals. There are three sub-families : — 



(a) ElapincB. These live on land and have a cylindrical tail. They 

 happen to be the only poisonous snakes known to Australia. Among 

 them are : — 



The Cobra-di-capello, or the snake with the hood, which when 



