. Revision of the Amphibia and Pisces of the Permian of North America. lpture, which is par-ticularly heavy over the posterior surface and radiates from a point near thelower edge (plate 12, fig. 4). The articular surface is as described by anterior to the articular region, on the inner side, there is a wide open-ing into the Meckelian cavity; there seem to be no anterior openings ofthis cavity, but two small foramina penetrate the jaw, one just below thearticular surface near the posterior end, and another directly below theanterior end of the Meckelian opening. The sutures which ha
. Revision of the Amphibia and Pisces of the Permian of North America. lpture, which is par-ticularly heavy over the posterior surface and radiates from a point near thelower edge (plate 12, fig. 4). The articular surface is as described by anterior to the articular region, on the inner side, there is a wide open-ing into the Meckelian cavity; there seem to be no anterior openings ofthis cavity, but two small foramina penetrate the jaw, one just below thearticular surface near the posterior end, and another directly below theanterior end of the Meckelian opening. The sutures which have been madeout are shown in fig. 38. There is a single series of irregular teeth on theedge of the jaw, except just anterior to the opening of the Meckelian cavity,where there is an oval patch of small, sharp teeth, about 3 cm. long, insidethe regular series and separated from it by a deep groove. The anteriortooth is somewhat larger than the others. A large pit on the inner surface,about 2 cm. from the anterior end, indicates the presence of a tusk on Fig. 38.—T. insignis. Inner view of right lower jaw. No. 4714 Am. Mus. X f. The vertebrcs are in general as described by Cope. The prominent char-acteristic is the divided or weakly united condition of the two halves ofthe neural spine. The first vertebra has a form similar to that of Eryops; the neural archis divided into two halves, each terminating in a sharp spine. These spinesare incHned backward and lie on either side of the enlarged spine of thesecond vertebrae. A small, button-like process lies on the anterior surfaceof each half just opposite the neural canal, and probably served for con- MORPHOLOGICAL REVISION IO9 nection with a rudimentary vertebra, anterior to the first, or with the posterior zygapophyses are of good size. There is a small second vertebra has a large, double spine, showing indications thatthe two halves were never firmly united. The posterior edge is broad,
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