262 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



OPHIDIA. 



Family CROTALID^. 



Genus CEOTALUrf. Linn. 



Ckotalus conflubntus. Say. 



Missouri Rattlesnake. 



Crotalus confluentus, Say, Long's Exped. R. Mts. ii. 1823, 48. — Be & GiR. Cat. N. Am. 



Reptiles, 1853, 8.— Bd. Pac. R. R. Rep. x. 1859, Reptiles of "Whipple's Route, 



40 ; pi. 24, f. 4.— Bd. U. S. and Mex. B. Surv. ii. pt. ii. Reptiles, 14.— Coop. & 



SucKL. Nat. Hist. Wash. Terr. 1860, 295, pi. 12.— Cope, Check List N. A. Bat. 



and Rep. 1875, 33. 

 Caudisona confluenta, Cope, App. Mitchell's Researches, 1861, 122.^-Cope, Proc. Acad. 



Nat. Sci. Phila. 1866, 307, 309.— Allen, Proc. Best. Soc. N. H. xvii. 1874, 69. 

 Crotalus lecontei, Hallow. Proc. Acad. Nat. Sci. Phila. vi. 1851, 180. — Hallow. Sit- 



greaves's Rep. Expl. Zufii and Colorado, 1853, 139, 147, pi. 18.— Hallow. Pac. 



R. R. Rep. X. 1859, Williamson's Route, Reptiles, 18, pi. 3. 

 Caudisona lecontei, Cope, App. Mitchell's Researches, 1861, 121. — Hayd. Trans. Am. Phila. 



Soc. xii. 1862, 177.— Cope, Proc. Acad. Nat. Sci. Phila. 1866, 307. 

 Crotalus cinei'eus, LeConte apud Hallow. Sitgreaves's Rep. Expl. Zufii and Colorado 



1853, 140 (in text). 



Specimens. 



1149. Sweet Grass Hills, Montana. July 29, 1874. 



1150. Sweet Grass Hills, Montana. July 29, 1874. 



1197. Black Coul6, near T^eton River, Montana. Sept. 6, 1874. 



1198. Black Coul6, near Teton River, Montana. Sept. 6, 1874. 



1199. Black Coul6, near Teton River, Montana. Sept. 6, 1874. 



The ascribed characters of G. lecontei, as compared with G. conflu- 

 entus, are found not to hold good when sufficient series are examined. 

 The number of superior labials in our specimens, and in others from the 

 Yellowstone, ranges from thirteen to sixteen, while in others eighteen 

 are described. Certain ascribed features of coloration are altogether 

 uncertain, as specimens vary interminably in the distinctness of the 

 dorsal blotches and in the details of the light markings about the head. 

 This appears to be due in part to age, as the smaller specimens are 

 usually the most boldly blotched, while on some of the largest examined 

 the markings are nearly obsolete. These statements are fully borne out 

 by our experience, we having noticed in this particular species that 

 the blotching cannot be relied upon as a distinctive character, as in some 

 individuals, notably from localities where the color of the soil is light, 

 the blotches in some instances are barely perceptible; moreover, the 

 forms of the blotches vary indefinitely, as some are serrated on their 

 borders, others present an unbroken line. The distinctness of the pat- 

 tern of coloracion also depends somewhat upon season, the markings 

 being clearest just after the shedding of the skin. There is certainly 

 no specific difference between the two supposed species, and vari- 



