OCR Text |
Show 240 DR. A. S. WOODWARD ON THE [Apr. 18, that the others as mounted (text-fig. 39, p. 233) are approximately in their natural order, each articulating with two adjoining vertebrae. Many, of course, are missing. The most anterior chevrons (text-fig. 46 A, p. 239) are normal, consisting of a pair of simple elongated lamina?, which are fused together in the long extension beneath the haemal canal, and are united by a very slight bridge of bone at their upper articular end. Further back, the extension beneath the haemal canal begins to shorten and widen into a triangular expansion, which ultimately becomes forked below ; and the upper ends of the chevron are no longer united even by a slender bony bridge. Still further back, the forked laminae of the two sides begin to be only partially and irregularly united in the middle line (text-fig. 46 B ) ; while near the end of the chevron-bearing middle part of the tail the laminae of the two sides remain quite separate, and each is forked at so wide an angle that it is practically a horizontal splint of bone which tapers to each end and is suspended by a knob at its middle (text-fig. 46 0). Fore Limb. The scapula (text-fig. 39 A, p. 233) is a long and slender blade, flattened on its inner face, gently convex on its outer face, and apparently very little expanded at its distal end, which is incomplete Text-fig. 47. Text-fig. 48. Text-fig. 47.- Cetiosaurus leedsi.- Right humerus, anterior aspect, and (A) transverse section showing internal cavity, c., internal core of rock representing a cavity ; d., deltoid crest; h., thickened head. About ^ nat. size. Text-fig. 48.- Cetiosaurus leedsi.- Upper portion of right radius (r.) and ulna (u.), anterior aspect; and (A) upper articular end of the same. About nat. size. |