2J2 Trans. Acad. Sci. of St. Louis. 



Pigmy Rattlesnake, the former serpent is provided with 

 a more powerful poison which makes up for the deficiency 

 in size of the venom conducting teeth and possibly a 

 smaller amount of poison discharged from them." 



So small is the rattle of this species that its whirring can 

 only be heard a few feet away. The Pigmy Rattler is fond 

 of frogs but will also eat small rodents and very young 

 birds. It is ovoviviparous. 



Genus crotalus. 



A pair of large, erectable, perforated poison fangs in front of the 

 upper jaw. Loral pit and rattle present. Top of head covered with 

 small scales. Dorsal scales keeled (outer sometimes smooth), with 

 pits, in 23-31 rows. Anals and subcaudals not divided. 



84. Crotalus horridus Linnaeus. Timber Rattlesnake. 

 Banded Rattlesnake. Northern Rattlesnake. 



Crotalus durissus, Crotalus horridus var. atricaudatus. Crotalus atricau- 

 datus, Crotalinus cyanurus, Caudisona liorrida. Uropsophus duris- 

 sus, Urocrotalon dtirissus, Caudisona durissus, Crotalophorus hor- 

 ridus, Yipera caudisona americana. 



Description. — Rostral higher than broad, prefrontals two. Tv/o nasals, 

 the anterior larger, nostril in the posterior one. Two rows of small 

 plates behind the nasals. Two anteorbitals, the upper the larger, the 

 lower smaller, forming the upper margin of the pit. Four to eight 

 scales between the supraoculars, tv^'o to four between the suborbitals 

 and labials. Upper labials fifteen, lower eighteen. A pair of large 

 elongated chin shields. Head broad, triangular, flattened above. Snout 

 blunt. Eyes small. Superciliaries large, projecting over the eye. 

 Pupil elliptical, vertical. Neck contracted abruptly behind the head. 

 Tail short, compressed, not tapering. Scales in 23-25 rows, strongly 

 keeled, excepting the outer row on each side, which is either smooth or 

 obsoletely keeled. Ventrals 165-178. Anal entire. Subcaudals 18-25, 

 undivided. 



Color. — Color above brownish yellow to almost black, posteriorly, with 

 transverse zigzag bands of chestnut brown, edged with black and bor- 

 dered outside the black with yellow, anteriorly with three series of 

 brovv-n spots bordered in the same manner. Beneath yellowish, more or 

 less blotched and speckled with black at the sides. Head uniform 

 brown above, with a wide brown band extending from the eye obliquely 

 downward and backward over the angle of the mouth. Tail black in 

 adults, banded in young. (Garman.) 



