. Bulletin. Natural history; Natural history. 76 Illinois Natural History Survey Bulletin Vol. 28, Art. 1 Juveniles differ from adults chiefly in size. The newly transformed toadlet is clearly recognizable as Fowler's toad. The partially grown specimen lacks the clearly defined tympanum of the adult. The parotoid glands are proportionately larger. The paro- toid length of seven specimens less than 40 mm. in body length averages per cent of the snout-vent length, whereas the aver- age parotoid length of seven adults over 58 mm. is per cent. The available series indicate an increasing
. Bulletin. Natural history; Natural history. 76 Illinois Natural History Survey Bulletin Vol. 28, Art. 1 Juveniles differ from adults chiefly in size. The newly transformed toadlet is clearly recognizable as Fowler's toad. The partially grown specimen lacks the clearly defined tympanum of the adult. The parotoid glands are proportionately larger. The paro- toid length of seven specimens less than 40 mm. in body length averages per cent of the snout-vent length, whereas the aver- age parotoid length of seven adults over 58 mm. is per cent. The available series indicate an increasing frequency, from south to north, of individ- uals with spotted breasts. This variation is not strictly clinal in nature, but a general trend is discernible, as shown in table 18. It is noteworthy that all of the 23 specimens available from the Henderson-Mercer coun- ty sand area in northwestern Illinois are spotted beneath and would therefore key out as B. americauus by the most frequently em- ployed character in anuran Fig. 63.—A subadult Bufo ivoodhousei foivleri from Tazewell County, Illinois. The ground- color is light gray, tan, or greenish gray; the spots are dark brownish black. Table 18.—Geographic variation in ventral pattern of Illinois Bufo woodhousei fowleri. Figures in parentheses are numbers of specimens. Characteristic Southern Half OF li (133i North-Central Illinois (47) Extreme Northwestern Illinois (23) Extreme Northeastern Illinois (14) Breast spotted (per cent ot specimens with) Pectoral spot only (per cent of specimens with) 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
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