. The tailless batrachians of Europe. Frogs; Amphibians. 14 INTEODUCTION. the tarsus is, of course, part of the foot proper; but as it hei'e forms a distinct segment, the term foot is used in a restricted sense. The foot is measured from the base of the metatarsal tubercle; it has five elon- gate toes, gradually increasing in length to the fourth, the fifth being again shoi'ter. There is in addition a rudimentary sixth toe, the so-called prse- hallux, conspicuous externally in the form of a tubercle or spur at the base of the inner toe. In Pelobates (Fig. 4, b) this preehallux or inner metatar
. The tailless batrachians of Europe. Frogs; Amphibians. 14 INTEODUCTION. the tarsus is, of course, part of the foot proper; but as it hei'e forms a distinct segment, the term foot is used in a restricted sense. The foot is measured from the base of the metatarsal tubercle; it has five elon- gate toes, gradually increasing in length to the fourth, the fifth being again shoi'ter. There is in addition a rudimentary sixth toe, the so-called prse- hallux, conspicuous externally in the form of a tubercle or spur at the base of the inner toe. In Pelobates (Fig. 4, b) this preehallux or inner metatarsal tubercle acquires a very great development, is covered by a horny sheath with sharp cutting edge, and serves as a shovel for digging in the soil. There is often another tubercle on the sole, at the base of the fourth toe; this so-called outer metatarsal tubercle (Fig. 4, o) is merely a thickening of the integument. Fig. A. Tia,n<i ol Alytes obstetricans. b. Foot ol Pelobates fiiscus. c. Foot oi Bufo calamita (lower views). Other dermal tubercles are usually present, more or less developed, single (Fig. 6, a, p. 16) or paired (Fig. 4, c), under the digits at the articulations between the phalanges; they are called subarticular tubercles. The fingers are free except in Hyla arhorea, in which they are provided with a rudimentary web. The toes are more or less webbed or bordered by membranes in all our Batrachians, but the extent of the web varies greatly according to the species, and is usually more developed in males than in females, especially during the breeding season. The web is usually smooth and transparent; it is thicker, and often warty, especially towards the margin, in 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 Boulenger, George Albert, 1858-1937. London, Printed for the Ray so
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Keywords: ., bookcentury1800, bookdecade1890, booksubje, booksubjectamphibians
