VOL. LXXIX.] - PHILOSOPHICAL TRANSACTIONS. 527 



the animal has any. Yet in that case they may.be very easily detected, by 

 drawing a pin, or any other hard substance, with a moderate degree of pressure, 

 along the edge of the jaw, from the apex to the angle of the mouth, when they 

 will be felt to grate against the pin, like the teeth of a saw. 



Though the size of the venomous fangs is very various, their situation is al- 

 ways the same; namely, in the anterior and exterior part of the upper jaw, which 

 situation he considers as the only one in which venomous fangs are ever found. 

 But as, in those serpents which are not venomous, common teeth are found in 

 that part of the jaw, it is plain that we cannot, by situation alone, distinguish 

 one from the other. They may however be easily distinguished, and with great 

 certainty, by the following simple operation. When it is discovered that there is 

 something like teeth in the fore-mentioned part of the upper jaw, let a pin be 

 drawn, in the manner described, from that part of the jaw to the angle of the 

 mouth; which operation may for greater certainty be tried on each side. If no 

 more teeth are felt in that line, it may be certainly concluded, that those first 

 discovered are what have been distinguished by the name of fangs, and conse- 

 uently that the serpent is a venomous one. If, on the contrary, the teeth first 

 discovered are found not to stand alone, but to be only a part of a complete row, 

 it may as certainly be concluded that the serpent is not venomous. 



In the upper jaw, both of venomous serpents and others, besides the teeth al- 

 ready spoken of, there are 1 interior rows ; consequently the distinction endea- 

 voured to be established might be expressed in other words, by saying, that all 

 venomous serpents have only 2 rows of teeth in the upper jaw, and all others 

 have 4. It may be better however to leave the interior rows out of the question, 

 as, in many species, the teeth of which they are composed are so small, as to 

 make it very difiicult to discover them. Indeed, in 1 species of anguis. Dr. G. 

 can hardly be sure that he has discovered them ; but as, in every other species he 

 has never failed to do so, with very little risk of error he may assert, that all 

 serpents whatever are furnished with them ; and that those only which are not 

 venomous have the exterior rows. 



What has been said sufficiently shows that Linnaeus's ideas, respecting veno- 

 mous serpents, were such as did not permit him to separate them from the 

 others ; if the method above proposed shall be found to render the distinction of 

 them sufficiently clear and easy, it naturally follows that they should be made 

 generically distinct. Some other reforms might also be made in Linnaeus's class 

 of amphibia, the consideration of which Dr. G. does not mean at present to 

 enter further into. But, before concluding, he thinks it necessary to notice an 

 inaccuracy of Linnaeus of a different kind from those above pointed out. In the 

 Preface to the Museum Regis, and in the Introduction to the class amphibia, 

 in the Sy sterna Naturae, Linnaeus says, that the proportion of venomous ser- 



