us most impressive illustrations of this variation. ]Most of these illus- 

 trations have been drawn from the publications of our countryman, Dr. 

 J. A. Allen, and relate to the winter birds of Florida. Allen made large 

 collections and took accurate measurements of thos^e portions of the body 

 which are especially depended upon by naturalists in determining species, 

 the length of body, wings, tail, tarsus, toes, and bill. All these parts were 

 found to vary independently of one another, and the variations from the 

 mean length often amounted to from 12 to 25 per cent, of the mean length. 

 While, too, most of the parts measured were not far from the mean on 

 each side, yet there were always a considerable number of individuals of 

 each species that furnished measurements wide of the mean. The same 

 principle is shown by Wallace to hold good among such lizards and 

 mammals as have been studied. AVhat is greatly needed is more extended 

 observations among all classes of animals. I have examined some of our 

 common snakes with reference to this matter of variation. We get the 

 specific characters among snakes from the number of rows of scales across 

 the back, the number br^ad plates along the abdomen and on the tail, 

 and from the kind and arrangement of the colors. Anybody who has 

 studied snakes has soon learned how extremely variable are their colors. 

 Among specimens of the spreading adder, for example, may be found 

 snakes of a plain gray or olive color without other markings, snakes with 

 mere indications of blotcTies. snakes with most conspicuous spots of bright 

 red or yellow and black, and snakes which are plain black. The other 

 characters vary to a perplexing extent. What are merely individual, or 

 at most, varietal peculiarities, have often furnished the basis for new 

 species. In order to bring before you the range of the variations in im- 

 portant parts of these animals, I present the results of estimates which 

 show how four species of our common snakes vary. ■■ 



These are the common garter snake [Euiainla sistalis), the black snake 

 {Bascanion constrictor), the smooth, green snake {Cydopfm vernal'k), and 

 the ring-necked snake {Diadophis pundaius.) From these it appears that 

 in the number of the body vertebrte the garter snake varies from the aver- 

 age to the extent of 14 per cent., the black snake 6 per cent., the green snake 

 only 4.5 per cent, and the ring- necked snake 13 per cent. In number of 

 caudal vertebrae, the garter snake varies 35 per cent., the black snake 20 



* The results here giveu have been deduced from the tables of measurements and 

 countsof ventral and caudal plates giveu in Baird and (Jirard's "Serpeuts of North 

 America." Any considerable collection of the species above studied would furnish 

 still sreater deviations from the means. 



