120 SEVENTH REPORT. 



CROTAT>IDAE. 

 The Pit Venomous Snakes. 



Genus 13, Agkistrodon Beauvais. Ang-kis-tro-don. — Moccasins. Copper Jieads, 



Cotton-mouth. 



Bodv and tail subcylindrical; dorsal scales in 21-27 rows, keeled; head very distinct, triangular, 

 covered with 9-12 plates which extend posteriorly beyond a transverse line between the eyes, a few 

 auxiliary scales are often present; two prefrontals; two preoculars, elongated longitudinally; two post- 

 oculars;' one or more suboculars; loreal 0-1; pupil vertical; anal plate enitre; tail short, tapering and 

 without a rattle. 



*One or more loreals; no true post-occipitals. 



1. Agkistrodon contortrix Linnaeus. — Cotton-mouth, Highland Moccasin, Rattlesnake Pilot, Red-eye. 



Dorsal scales in 23-25 rows; loreal present, partly bounding *he pit on the front; two preoculars, 

 the lower bounding the pit posteriorly; two postoculars; two or more suboculars; often a subloreal is 

 present, which with the second superior labial bound the loreal pit below; temporals smooth, lower 

 row largest; superior labials 8, (7); inferior labials usually 10: postoccipital plates; length 800-1000 mm. 

 Color grayish to light hazle or reddish brown mottled with small dark points. On each side is a series 

 of 15-2.5 "darker chestnut colored blotches resting upon the ventrals and abruptly contracting about 

 the middle of the sides. These blotches extend to the vertebral line where they may end abruptly 

 or be more or less rounded or even confluent. Top of head often bright copper colored, without stripes, 

 except the postorbital bands; sides of the head cream colored; chin and throat yehowish white, often 

 mottled but not spotted; abdomen light copper color to yellowLsh, with a series of distinct black spots 

 on each edge; tail terminating in a long point, often yellowish or greenisli in young specimens. East- 

 ern, Austrariparian and eastern part of the central regions. It is very doubtful if it is in the state. 



Genus IJ^, Crotalus Linnaeus — Kro-ta-lus. — Rattlesnakes. 



Body robust, cylindrical ; dorsal scales in 21-31 rows ; head more or less triangular and distinct, usually 

 covered with scales and plates; loreal pit very distinct ; temporals and labials numerous, pupil ver- 

 tical; tail terminating in a button or rattle. This genus is found chiefly in North America. The rattle- 

 snakes are rather slow in their movements and not quick to bite. They coil up, raise the head, give 

 a warning with the rattle and .sjjring at their enemy. They can spring forward a distance about equal 

 to two-thirds the length of their own bodies. They are all venomous, and seem to thrive best in rocky 

 regions. 



*Top of head covered with numerous small scales or plates; supraoculars normal. 



JTail black; dorsal spots chevron-shaped cross-bands 



1. Crotalus horridus Sinnaeuc. — Banded Rattlesnake. 



Dorsal scales in 23-25, (27) rows; head very distinct, triangular; rostral high; anterior nasal large and 

 in contact with the rostral; cephalic scales small and numerous; two rows of small plates behind the 

 nasals; 4-8 rows of scales between the subraoculars; 2-4 rows of scales between the suboculars and 

 the superior labials; superior labials 12-16; inferior labials 13-15; loreals two; temporals numerous. 

 General color variable, from light vellow and reddish gray to dark brown or black, crossed by twenty 

 or more irregular chevron-shaped black bands. These bands are often broken into angular spots on 

 the sides, but they always form zigzag cross-bands; a postocular band passes above the angle of the 

 mouth; tail of adiilt specimens imiformly black; length 900-1500 m m. From Maine to Florida, west 

 to Iowa and Texas. Rare in Michigan. Found in the Au Sable region and Kalamazoo county. 



Genus 15, Sistrurus Garman. — Sis-tru-rus. — Ground Rattlesnakes. Massasaugas. 



Body small to medium stout; dorsal scales in 21 -25, (27) rows, mostly keeled, with apical pits; top 

 of head covered with large plates which extend posteriorly beyond a transverse line between the 

 eyes; rostral moderately large; nostril between two plates; labials and temporals rather small; one 

 pair of geneials; gular scales small; pupil vertical; loreal pit and rattle present; anal plate entire. 



♦Postnasal usually in contact with the upper preocular; light band, to the angle of the mouth, be- 

 gins at the nasal plate. 



1. Sistrurus catenatus Raflnesque. — Massasauga. 



Dorsal scales in 23-25, (27) rows; one or two inferior rows smooth; rostral higher than wide, irregu- 

 ular hexagonal; preoculars 2-3, upper larger, usually in contact witli the nasal, anterior end oblique 

 upwards, usually covering the loreal; superior labials 12-14; inferior labials 11-14; no large loreal, 

 occasionally a small upper one; one row of scales between tlie suboculars and superior labials. Gray, 

 brown or even black, with a dorsal series of dark brown blotches, anteriorly often crescent shaped, 

 posteriorly subcircular. There is a second series of roundish, indistinct spots, more or less alternating 

 with the dorsal spots; a third series opposite the dorsal spots and a fourth series on the inferior rows 

 and ends of the ventrals; top of head with a light band across the anterior end of the frontal; also a 

 light line extends from the postnasal plate below the orbit to the angle of tlie mouth; usually two dark 

 bands from the subraoculars to the first dorsal spot; abdomen yellowish to black. The color varies 

 with age, seaspn of the year and habitat. 



tDorsal scales in 25, (23-27) rows; dorsal spots usually fewer than 40. 



