. The biology of the amphibia. Amphibians. SEX AND SECONDARY SEX CHARACTERS 125 the upper jaw. No male frogs are known to fight with their teeth for the possession of the female, nor do rubbing movements of the jaws as in Hydromantes (Fig. 47) play any part in court- ship so far as is known. Hence, as in the case of Eurycea, a func- tional significance for the dental hypertrophy is doubtful. Nevertheless, the same apparent changes in linkage seen in the plethodontids occur in frogs. In the neotropical Hemiphractus and Amphodus, the dorsal margin of the prearticular is hyper- trophied into a ro
. The biology of the amphibia. Amphibians. SEX AND SECONDARY SEX CHARACTERS 125 the upper jaw. No male frogs are known to fight with their teeth for the possession of the female, nor do rubbing movements of the jaws as in Hydromantes (Fig. 47) play any part in court- ship so far as is known. Hence, as in the case of Eurycea, a func- tional significance for the dental hypertrophy is doubtful. Nevertheless, the same apparent changes in linkage seen in the plethodontids occur in frogs. In the neotropical Hemiphractus and Amphodus, the dorsal margin of the prearticular is hyper- trophied into a row of pseudoteeth in both sexes. Hemiphractus. Fig. 47.—The elongated teeth in the upper jaw of the male Hydromantes platycephalus apparently serve as stimulating organs during courtship. The males of other species of the genus rub the females with their chin and teeth during this period. goes farther than Dimorphognathus in the development of excess bony growths, for its whole skull has become evolved in a gro- tesque casque of secondary dermal bone. The exact form of the tooth varies with the species in both frogs and urodeles, although tooth characters have been rarely used in defining species. The hypertrophy of the teeth is not always correlated first with one sex and later with both. In Ceratophrys the smaller species have bicuspid teeth in both sexes; the larger, monocuspid elongate ones. In young speci- mens of the large species such as C. dorsata, the teeth arise as monocuspid structures. A similar loss of one cusp, apparently the outer, occurs in the phylogeny of Aneides; the smaller species, aeneus, having bicuspid teeth in both jaws for a long period, the larger, lugubris, developing many monocuspid teeth directly. On the other hand, many large species of both frogs and sala- manders have bicuspid teeth, and small species, such as Leptopelis brevirostris and Phrynopsis usumbarae as well as various pipids, have elongate monocuspid ones, showing that there is no corr
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Keywords: ., bookcentury1900, bookpublishernewyorkmcgr, booksubjectamphibians
