. plates. They are regularly but very gently concave superiorly and convex inferiorly. Contrary to Marsh I have interpreted the thick, narrow, rugose extremities of these bones as the posterior and the thin, broadly expanded extremities as the anterior. I believe these bones to have been closely applied and firmly united by cartilage throughout three fourths of their total length as indicated b}' the long, straight, rugose margin which extends from tlie thickened extremity throughout three fourths the total Icngtli of tliL' Ijone and which I liave interpreted as the inner margin of each sterna
. plates. They are regularly but very gently concave superiorly and convex inferiorly. Contrary to Marsh I have interpreted the thick, narrow, rugose extremities of these bones as the posterior and the thin, broadly expanded extremities as the anterior. I believe these bones to have been closely applied and firmly united by cartilage throughout three fourths of their total length as indicated b}' the long, straight, rugose margin which extends from tlie thickened extremity throughout three fourths the total Icngtli of tliL' Ijone and which I liave interpreted as the inner margin of each sternal. The outer margin of each sternal is then slightly emarginate, thin and smooth, wliilc anteriorly they are broadly pointed and rugose. Thus the sternum of DiplodocKS may be considered as comi)osed of two liroad plates of bone arranged one on either side of the median line, with their longer axes parallel with the longitudinal axis of tlie skeleton. These bones were firndy united ])y cartilage throughout three fourths of their length. They are contracted and thickened posteriorly where they pre- sent a broad rugose surface for the attach- ment of the cartilaginous xiphisternum and sternal ribs. Anteriorly they expand into bi-oad thin plates with rugose anterior margins by means of which they were attached to the coracoids and thus with the scapidar arch possibly without the intervention of ossified clavicles or interclavicles. Taken together the sternals of Diplodocus would thus form a shallow, raft-like sternum, the individual elements of which have, a certain resemblance to those found in Iguana, in which animal, however, they are separated throughout a considerable portion of their length by the interclavicle and are contracted both anteriorly and posteriorly. The connection between the ribs and sternum was chiefly posterior and not lateral as in the Ratittc, and doubtless took jjlace through well-developed cartilaginous or imperfectly ossified sternal ribs and xiphisterni.
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectdiplodo, bookyear1901
