O F S E R P E N T S; ' 187 



III. Thofe which have large fcales under the belly and tail, but their 

 extremity is terminated by a moveable and articulated rattle. 



IV. Thofe whofe fcales ur\der the belly and tail are like thofe of the 

 back. 



V. Thofe encircled by fcaly_ rings, ufually called ampbijbena. 



VI. Thofe whofe fides have folds, not ribs, named ccecilia, 



VII. Thofe whofe body, next the head, fhews great fcales; then the 

 body fhews fcaly rings: the tail alfo fliews thcfe rings at its origin, and 

 fimple fcales at its extremity. 



VIII. Thofe whofe (kin is replete with little tubercles. 



In thefe fhould be formed a divifion of thofe viviparcus, properly 

 called vipers j and thofe oviparous. This diflindtion is not eafy to afcer- 

 tain : but it is fuggefted that all vipers are venomous ; confequently may 

 be diftinguifhed by their fangs, which are always diftinft from their teeth. 

 It has been fuggefted, alfo, that thofe which had fangs were generally, 

 yet with exceptions, on the fummitof the head covered with fmall fcales, 

 nearly like thofe of the back : all others having in that part larger fcales, 

 of a very different form, always nine in number, and placed in three 

 rows; the firft and fecond (counting from the nofe) compofed of two 

 fcales, the third of three, and the fourth of two. Not only the colours 

 ef ferpents vary, between the young and the old ; but alfo the number of 

 fcales on their bodies, the oldeft having the moft. It is vain ta attempt 

 their arrangement by colours, as fometimes young of feveral different 

 colours fhall iffue from one parent. 



OF VENOMOUS SERPENTS IN GENERAL. 



TH E poifon of ferpents has ever been one of the greateft objeds of 

 human confideration. The glands that ferve to fabricate this ve- 

 nomous fluid, are fituated on each fide the head, behind the eyes, and have 

 canals leading from thence to the bottom of the fangs in the upper jaw, 

 where they empty into a kind of bladder, from whence grow the fangs 

 on each fide. 



When the ferpent is irritated to give a venomous wound, it opens its 

 formidable jaws to their wideft extent: the moveable bones of the upper 

 jaw Aide forward ; the fangs, that lay before inclining, are thus erefted; 

 they are ftruck with force into the fiefh of the objed bitten j by meeting 



• , refiftance 



