REVISION OF THE KING SNAKES. 15 



genus. It is included here only on the possibility that it may be of 

 value in establishing relationships with other genera. The real value 

 of the labial count in the present study is the sure indication it gives 

 of the degree of specialization of the form. Any marked change in 

 the normal 7-9 formula is, in the present genus, an earmark of 

 specialization. We may call attention here to the following forms 

 that show conspicuous departure from the 7-9 arrangement: Con- 

 juncta, micropTiolis, pyrrhomelaena, jloridana, elapsoideSf virginiana, 

 rhomhomaculata, and calligaster. The descriptions and discussions 

 following will make it clear that these are the most specialized forms 

 in the genus, and in several instances occupy, geographically, the 

 most isolated portions of the entire range. 



Variation in other features of scutellation. — The caudals and ventrals 

 vary geographically, sexually, and individually. A brood of eight 

 young of triangulum from Indiana shows a range in ventrals of from 

 200 to 208; of these, 5 are females and 3 males, and their averages 

 are respectively 205 and 203. This expresses fairly well the average 

 difference between the sexes in the number of ventral plates for any 

 form in the genus. Sometimes a large series will show an average 

 difference of only half a plate in favor of the females. The influence 

 of sex on these averages is therefore negligible when they are to be 

 used to show geographic differences. And as the latter undoubtedly 

 occur the number of ventrals proves to be an important character 

 in the determination of relationships. 



The caudals show a more distinct relation to sex than the ventrals. 

 The males always average to have a higher number, sometimes only 

 one or two, but usually four or five, more than the females. Geo- 

 graphic differences in their number can be satisfactorily demonstrated 

 only by comparing averages of like sexes. As this always reduces the 

 dependability of the averages by reducing the number of specimens 

 upon which they are based, the caudals are much less valuable in 

 the present study than the ventrals. In subspecific determination the 

 number of caudals may be of more value than the proportionate tail 

 length, since the latter may remain the same throughout a series of 

 closely allied forms, while the ventrals and caudals are increasing or 

 decreasing together. 



The temporals are normally two in the first row, three in the second, 

 and four in the third, expressed: 2 + 3+4 (fig. 3). Variation in some 

 forms is normally by increase of a scute in any row, more often in 

 the last row (getulus, pyrrhomelaema, calligaster), in others it is 

 normally by decrease (syspila, triangulum), but in only a few forms 

 has this formula been altered racially. In elapsoides, virginiana, and 

 micropTiolis the temporals are usually 1+2 + 3. Reduction in the 

 temporals takes place by a decrease in size of the upper scute in each 



