Page:The Scientific Monthly vol. 3.djvu/618

 6i2 THE SCIENTIFIC MONTHLY

fringe-finned fish ancestors ; with the loss of these scales moat of the Amphibia also lost the power of forming a bony dermal armature.

Recent researches in this country, chiefly by Willieton and Case, indicate that the solid-headed Amphibia (Stegocephala) and primary forms of the Rcptilia chiefly belong to late CarboniferouB (Pennsyl- vania) and early Permian time. They are found abundantly in pool deiKMiits widespread over the southwestern United States and Europe associated in rocks of a reddish color, which point to aridity of climate in the northern hemisphere during the period in which the terrestrial adaptive radiation of the Amphibia occurred. These arid conditions continued during the greater part of Permian time, especially in the northern hemisphere. In the southern hemisphere there is evidence even of a period of Dxtensive glaciation, which was accompanied by the dis- api>earance of the old lycopod flora (club mosses) and arrival of the cool fern flora (Gloxsopferis) which appeared simultaneously in South America, South Africa, Australia, Tasmania and southern lodia. The widespread distribution of this flora in the southern hemisphere fur- nishes one of the arguments for the existence of the great South Pacific continent Gonduana, a hypothesis of Suess which is supported by Schuchert. In North America Permian glaciation was only local. The last of the great Paleozoic seas disappeared from the surface of the continents, while the border seas give evidence of the rise of the ammonite ceplialopods. Toward the close of Permian time the conti- nent was completely drained. Along the eastern seaboard the Appa- lachian revolution occurred, and the mountains rose to heights esti- mated at from three to five miles.

��Fio. ?S. Skeleton of Ervopi fboh thi PCBUo-CiBBONirEBOcB of Texas, typ* at th* tteKorpphitllnn Amphlblnu* whlcb w«re structurally aiiMCtr*! to lb« Labyrlnth- odoDta of the Trlawilc. Mounled In tb« American Musfum of Nntural History,

Evidences of extensive continental connections in the northern hemisphere are found in the community of type between the great ter- restrial amphibians of such widely separated areas as Texas and Wiirt- temberg which develop into similar resemblances between the great Labyrinthodont amphibians of Lower Triassic times of Europe, North America and Africa. Ancestral to these Triassic giants is the large, sluggish, water- and shore-living Enjops of the Texas Permian, with

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