Reptiles and Amphibians of Illinois. 313 



except the two outer rows of each side. Rostral plates exca- 

 vated below. Anterior nostril much the larger, reaching the 

 posterior nasal and in contact above with prefrontal and su- 

 praciliary. Inferior anteorbital about half as wide. About 

 four postorbitals and suborbitals. Supralabials small, about 

 thirteen. Infralabials thirteen. Dorsal rows twenty-five. Ven- 

 trals 140. Subcaudals 28, generally a few posterior plates 

 divided. 



Color above gray to blackish brown, with a dorsal series 

 of about forty chestnut-brown spots edged with black, and 

 outside the latter color narrowly margined with white. On 

 each side two or three series of smaller brown spots similarly 

 margined. First dorsal spots with two arms which extend 

 forward to the parietal plates. A wide brown band extends 

 from the eye over the angle of the mouth and terminates on 

 the side of the neck ; it is margined above with pale yellow 

 and below by a yellow bar which extends from the inferior 

 anteorbital across the angle of the mouth. Superior labials 

 mostly brown. Beneath thickly blotched with black, paler 

 anteriorly. 



Total length, 25.50 ; tail, with four rattles, 3 inches. 



Prairies throughout the State. Cook Co. (Kennicott), 

 Galesburg, Peoria (Brendel), Pekin, Normal, Farmer City. 



Ancistrodon, Beauv. 



Beauvais, Agkistrodon, Trans. Am. rhil. Soc, 1799, p. 381. 

 Dum. et Bibr., Trigonocephalus, Erp. Gen., 1854, VII.. p. 1488, 

 S. Garman, Ancistrodon, Mem. Mus. Comp. Zool., 1883, p. 120. 



With symmetrical plates on the head. Loreal present or 

 absent. Pit between the eye and nostril large. Fangs and 

 poison glands well developed. Dorsal scales in from twenty- 

 three to twenty-five rows, all strongly carinated. Posterior 

 subcaudal plates divided. No rattle. Body short. Tail short, 

 terminating in three elongate plates. Terrestrial or aquatic. 



Includes the poisonous copperhead and the water moccasin. 



Scales in 23 rows. Loreal present. * Terrestrial . . A. contortkix. 

 Scales in 25 rows. Loreal wanting. Aquatic. . . A. piscivorus. 



