. Bulletin. Natural history; Natural history. November, 1961 Smith: Amphibians anh 'tiles of Illinois 271. Fig. 251.—An adult Crotalus horridus horridus X atricaudatus intergrade from Jackson County, Illinois. The groundcolor may be pale gray, greenish white, or yellowish white; the bands are sooty black; a vague, middorsal rust-colored stripe is present on the anterior part of the body. Table 90.—Sexual variation in Illinois Crotalus horridus. Figures in parentheses are num- bers of specimens. Characteristic Ventrals Caudals Tail length as percentage of total length Males (14) Females (15
. Bulletin. Natural history; Natural history. November, 1961 Smith: Amphibians anh 'tiles of Illinois 271. Fig. 251.—An adult Crotalus horridus horridus X atricaudatus intergrade from Jackson County, Illinois. The groundcolor may be pale gray, greenish white, or yellowish white; the bands are sooty black; a vague, middorsal rust-colored stripe is present on the anterior part of the body. Table 90.—Sexual variation in Illinois Crotalus horridus. Figures in parentheses are num- bers of specimens. Characteristic Ventrals Caudals Tail length as percentage of total length Males (14) Females (15) Range Mean Range Mean 162-174 21-30 163-178 19-23 I body; a dark postorbital bar usually present on each side of head. Variation.—The male of the timber rat- tlesnake has a slightly lower ventral count average than the female, table 90. The juvenile differs from the adult most markedly in the presence of a terminal "but- ton" rather than a rattle and in having a lighter groundcolor. Tail rings are some- times visible on young snakes; the tails of subadults and adults are uniform black. On the basis of the number of scale rows at mid-body and average adult size, the rat- tlesnakes of extreme southwestern Illinois are referable to the Coastal Plain race, Cro- talus horridus atricaudatus, table 91. In ventral count averages and most details of pattern these snakes resemble the more northern specimens. Specimens from the Mississippi River counties of Illinois from Jackson County southward are therefore regarded as C. h. horridus X atricaudatus'. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Illinois. Natural History Survey Division. Urbana, State of Illinois, Dept. of Registration and Education, Natural History Survey Division
Size: 1676px × 1491px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., booka, bookcentury1900, bookdecade1910, booksubjectnaturalhistory
