Title: Bulletin
Identifier: bulletin2819611963illi (find matches)
Year: 1918 (1910s)
Authors: Illinois. Natural History Survey Division
Subjects: Natural history; Natural history
Publisher: Urbana, State of Illinois, Dept. of Registration and Education, Natural History Survey Division
Contributing Library: University of Illinois Urbana-Champaign
Digitizing Sponsor: University of Illinois Urbana-Champaign

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206 Illinois Natural History Survey Bulletin Vol. 28, Art. I
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Fig. 197.—An adult Elaphe obsoleta spiloides from Pope County, Illinois. The groundcolor is gray; the blotches are black or dark brown. Diagnosis.—A subspecies of Elaphe ob- soleta (largest Illinois specimen 1,690 mm. in total length), fig. 197, differing from E. o. obsoleta in the retention of a distinctly blotched pattern throughout life. The 26 to 32 dark dorsal blotches and alternating lateral spots on a gray groundcolor can be counted readily on the largest adults. Variation.—Sexual dimorphism and on- togenetic variation are evidently the same for E. 0. obsoleta and spiloides except that spiloides adults do not differ so strikingly from juveniles. Only 1 of 12 adult and subadult specimens of spiloides at hand is so dark that the body blotches cannot be readily counted. The counts of body blotches on the remaining 11 specimens range from 26 to 31 (average 29.4). For the 12 specimens, the tail length ranges from 14.7 to 18.4 (average 16.4) per cent of total length. Scutellation data are almost identical with those of Illinois speci- mens of E. 0. obsoleta except for the slightly higher frequency of specimens with 27 scale rows on the anterior half of body. Ten speci- mens display the following variation: an- terior scale rows 24 in 16.7 per cent, 25 in 33.3 per cent, 27 in 50.0 per cent; scale rows at mid-body 25 in 33.3 per cent, 27 in 66.7 per cent; posterior scale rows 17 in 50 per cent, 19 in 50 per cent; ventrals in males 227 to 238 (average 231.1), in females 230 to 235 (average 233.1) ; caudals in males 78 to 86 (average 82.0), in females 73 to 79 (average 76) ; supralabials 8 + 8 in all; infralabials 11 -f 11 in 42 per cent, 11-1-12 in 29 per cent, 13-1-13 in 29 per cent; preoculars 1 + 1 in all. Habits.—The gray rat snake, more often called chicken snake in Illinois, is similar in behavior, feeding habits, and reproduc- tive habits to E. o. obsoleta. Individuals often enter buildings in search of rodents. Illinois Distribution.—Individuals iden- tical with Gulf Coast spiloides in pattern occur rather consistently in extreme south- eastern Illinois, fig. 196. The habitat of spiloides is similar to that of obsoleta. Speci- mens referable to obsoleta X spiloides inter- grades have been taken in Alexander, Ham- ilton, Jackson, Lawrence, Union, and Wabash counties. Although undocumented by specimens, a published record for the following locality

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