764 



REPORT OF NATIONAL MUSRUM, 1898. 



bright yellow, aud sometimes even red. It may also liaj)peu tliat, by 

 the confluence and extension of the darker margins, we have light bars 

 on a dark gronnd, as on a specimen from the Scioto Valley, Ohio, 

 where, with the other characters similar, the color is of a dark brown 

 above and on the sides, with transversely (luadrate brownish ash-col- 

 ored spots along the back, some one and a half or two scales long, nine 

 or ten wide, and at intervals of about three scales. Of these spots 

 there are twenty eight from head to anus, and about nine on the tail, 



wheic they form half 

 rings, with intervals a 

 little larger than them- 

 selves. 



About forty specimens 

 display the normal col- 

 oration. In eleven the 

 lateral spots of the first 

 row join the spots of the 

 median row, inclosing 

 the light intervening 

 dorsal spaces as spots. 

 In four other specimens 

 this fusion is imperfect. 

 The light spots have ac- 

 quired so dark a shade 

 as to have disappeared 

 in the black color variety, called by Dr. Holbrook Heterodon niger. 

 Among numerous specimens of this form in the national collection 

 there are two (Cat. Nos. 1168 and 9105) in which traces of the usual 

 spots remain. 



One specimen of this form is a true lead color, with a black band 

 extending posterior to the orbit (Cat. No. 16189). 



The specimens on which Baird and Girard proposed the name Hete- 

 rodon atnioides differ from the normal form in a less production of the 

 free acute edge of the rostral plate. No other character reenforces this 

 peculiarity, and it intergrades with the usual type. It can be looked 

 upon only as an individual characteristic. Individuals of this kind 

 are more frequently sent from the eastern part of the Austroriparian 

 region than elsewhere. 



The specimen on which the H. cognatus (Cat. No. 1271; Indianola, 

 Texas) was proposed by Baird and Girard is lighter colored than usual, 

 but not otherwise different, except in the possession of only two tempo- 

 rals in the first row on each side. The absence of the small superior 

 temporal is not by itself indicative of important diversity. 



Fig. 166. 



Heterodon platyrhinus Latkeille. 



= 1. 



