526 PHILOSOPHICAL TRANSACTIONS. [aNNO 1780. 



Linnaeus thought the fangs might be distinguished by their mobility ; this at 

 least, may be fairly inferred, from his never mentioning them in the Museum 

 Regis, without adding the epithet mobilia, except in one instance, the coluber 

 aulicus. But with regard to mobility, considered in general as a character of 

 venomous fangs, Dr. G. has not only never found it so, but he has also never 

 been able to discover in them any thing which could properly be called mobility. 

 He has indeed sometimes found some of them loose in their sockets ; but then 

 he has found others, in the same specimen, quite fixed. The same thing was 

 observed both by Dr. Nicholls, and by the Abbe Fontana, in the common viper, 

 even during life. The loose fangs may be such as have not yet been firmly fixed 

 in their socket, or they may have been loosened by some accident: for the fangs 

 may be at any time loosened, and even displaced, by a small degree of violence; 

 which perhaps may be one reason why there is always a certain number of small 

 fangs, near the base of the full grown ones, ready to enlarge and take their 

 place, if they should be by any accident torn out. 



Linnaeus seems also to have thought that the fangs might be known by their 

 situation. In the Introduction to the class Amphibia in the Systema Naturae, he 

 says they are, " Dentibus simillima sed extra maxillam superiorem collocata;'' 

 and in the description of the crotalus dryinas, in the Amoenitates Academic£e, 

 he says, " Dentes ejus duo canini uti in reliquis venenatis serpentibus non in 

 maxillis haerent, iis enim vulnerando, non autem ictus infligendo utitur." These 

 2 quotations show that Linnaeus thought the situation of the fangs different from 

 that of the common teeth; the last also shows that he thought their mode of 

 action influenced by it. But the most singular opinion of Linnaeus, respecting 

 the venomous fangs, was, that they were sometimes fixed in the base of the 

 jaw. Of this he has given 2 instances in the Museum Regis. One in the de- 

 scription of the coluber severus, of which he says, " Hastae mobiles solitariae 

 versus basin maxillarum interius adhaerent." The other in that of the coluber 

 stolatus. His words there are, " Tela mobilia ad basin maxillarum affixa, ut 

 vix vulnerare valeat hostes, solum cibos veneno inficere." 



With respect to their size, it has already been observed that it is very various, 

 consequently no certain judgment can, in all cases, be made from that circum- 

 stance. In some species they are so large, that their size alone sufficiently dis- 

 tinguishes them from common teeth; but in others they are so small, that it is 

 very difficult to discover them. The size of the common teeth also varies very 

 much, in diflterent species. In the coluber mycterizans they are remarkably 

 large, especially those which are situated near the apex of the upper jaw; which 

 circumstance probably helped to lead Linnaeus into the erroneous opinion he en- 

 tertained, that this serpent was venomous. But in many species the teeth are so 

 small, that it is impossible to discover, merely by looking into the mouth, that 



