File:Bulletin (1961) (19807167773).jpg

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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118 Illinois Natural History Survey Bulletin Vol. 28, Art. I Chelydra strpentina. Some authors prefer to include the family Kinosternidae in the Chelydridae. Chelydra Schweigger The genus contains only two species, one restricted to Central America and one oc- curring from southern Canada to Ecuador. The wide-ranging species contains two sub- species, one of which, the nominate sub- species, occurs throughout Illinois. Chelydra serpentina serpentina (Linnaeus) Common Snapping Turtle Testudo serpentina Linnaeus 1758:199 (type locality: "warmer regions"; revised to vicin- ity of New York City by Schmidt 1953). Chelonura serpentina, Kennicott 1855:591. Chelydra serpentina, Davis & Rice 1883^:32. Chelydra serpentina serpentina. Pope 1939:72- 83. Chelydra sp., Cagle 1944^:105. Chelydra, Cagle & Chaney 1950:388. Diagnosis.—A large aquatic turtle (larg- est Illinois specimen approximately 300 mm. from anterior to posterior end of carapace), fig. 107, with an enormous head, thick, pow- erful legs, and a relatively long tail; cara- pace in 5'oung with 3 longitudinal keels, in adults with keels worn of¥ but rough and usually coated with algal growth; posterior edge of carapace serrate; plastron cruci- form and inadequate to conceal legs, neck, and tail; head pointed, covered with tuber- culate skin; jaws strong; small, paired gular barbels; eyes dorsolateral in position; underside of tail plated with large scales; in young, groundcolor black, with some olive or gray mottling and spotting on sides of head, plastron, and underside of soft parts; subadults and adults dirty olive, gray, or brownish black above, with some evidence of radiating rows of dark flecks on each cara- pace plate, or carapace almost patternless; soft parts gray or light olive; beak with nu- merous dark dashes. Variation.—The basal portion of the tail is on the average longer in the male than in the female of the snapping turtle, and the vent is posterior to the rear edge of the carapace. In the female the anus is usually about even with the posterior edge of the carapace. Although several proportional ratios have been tested in an attempt to findj a method for sexing this turtle by externalj characters, none has proved reliable. Part) of the difficulty in sexing these turtles is duel to a remarkable change in proportionate tail; length as the turtle becomes larger.
Text Appearing After Image:
Fig. 107.—An adult Chelydra serpentina serpentina from Vermilion County, Illinois. Young specimens are predominantly black; older individuals are dirty olive or brownish black. Most large specimens have growths of algae on the carapace.

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