. Revision of the Amphibia and Pisces of the Permian of North America. 9 The single sacral rib is large, with a single head, divided into distinctfacets, which lie at an angle to each other and fit the facets on the pleuro-centrum and transverse process, and the intercentrum. A slight constric-tion forms a neck which separates the head from the body of the rib. Thebody is flattened and curved to the rear; the outer surface fits accuratelyinto a depression, which runs obliquely across the inner face of the iliumfrom above backwards and downwards. There is no rugosity on either boneat the points
. Revision of the Amphibia and Pisces of the Permian of North America. 9 The single sacral rib is large, with a single head, divided into distinctfacets, which lie at an angle to each other and fit the facets on the pleuro-centrum and transverse process, and the intercentrum. A slight constric-tion forms a neck which separates the head from the body of the rib. Thebody is flattened and curved to the rear; the outer surface fits accuratelyinto a depression, which runs obliquely across the inner face of the iliumfrom above backwards and downwards. There is no rugosity on either boneat the points of contact, but the two fit very closely. This relation of thesacral rib to the ilium is of great importance, as on it depends the positionof the whole pelvis. The relationship is confirmed by its occurrence in threespecimens. The caudal ribs are free as far back as the fifth vertebra, but ribs areabsent beyond this. The shoulder girdle and fore limbs (No. 4186 Am. Mus.): This is the speci-men figured by Cope. The anterior portion of the clavicle is broad and some-. FiG. 30.—Eryops megacephalus. A. Inner view of left sacral rib and ilium, showing relation of bones. No. 4292 Am. Mus. X H- B. Inner view of left sacral rib. No. 4307 Am. Mus. X }4. C. Outer view of same. what convex outward; the bones of the two sides overlap in the specimen,and probably did so to some considerable extent in the living animal. Theposterior third is bent almost at right angles to the anterior part, and lieson the upper edge of the scapula, overlapping it somewhat on the inner side;this part of the clavicle lies beneath the anterior end of the cleithrum. Theedges of the clavicle are thin, and the anterior and posterior edges show atendency to fray out into thin projections, but a strengthening ridge runsits full length, about one-third of the way from the top. The outer surfacesof both the clavicle and interclavicle are smooth and without radiatingridges. The interclavicle is rhomboid in form with
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Keywords: ., bookcentury1900, bookdecade1910, bookidc, booksubjectpaleontology
