Morphological Variations in Vipera berus. 9 



principle to lay down, that scaling, and scaling only, is to be 

 taken into consideration in determining the validity of a 

 species. Of all the characters of adders, their scaling is the 

 character which is most liable to variation, yet it is regarded 

 as of specific importance. Size and colour, even when con- 

 stant and not varying nearly so much as scaling does, are 

 disregarded as of no importance in settling species validity ; 

 otherwise it would be at once seen that the small red viper 

 is no more an adder than it is any other serpent. Its size 

 and colour are always different from those of V. herus, but 

 it has the same scaling as is set down characteristic of the 

 adder. There seems to me no valid reason why it should 

 not have this same scaling, but it is surely absolutely in- 

 sufficient to class the reptile as an adder on that account, 

 seeing the great differences in other characters. The more 

 one studies scaling, the more one sees how uncertain it is 

 in a species, how greatly it varies, and what wide limits have 

 to be set in order that it may include all that occurs in those 

 snakes which are undoubtedly of the same species. 



II. On the Trapezium (os multangulum majus) of the Horse. 

 By 0. Charnock Beadley, M.B., F.RS.E. 



(Eead 24th October 1904.) 



The palseontological evidence of the evolution of the horse 

 is now so considerable, that the constitution of the equine 

 manus and pes offers few morphological problems apart from 

 those which are associated with the similar parts of mammals 

 in general. But before the discovery of fossil remains of its 

 predecessors, it was not by any means easy to account for 

 the striking reduction in number and modification in form of 

 the carpal, tarsal, metacarpal, and metatarsal bones, and the 

 bones of the digit of the modern horse. So far as can be 

 discovered from the recorded views of those living before the 

 middle of the eighteenth century, no suspicion that the horse 

 was other than a monodactyl animal ever entered into the 

 minds of morphologists. Buffon and Daubenton were evi- 

 dently the first to trace any features which could be held as 

 showing that the horse has more digits than one. Daubenton 



VOL. XVI. B 



