oGO Annals of the Carnegie Museum. 



slightly fixed in the original matrix. After this bed had hardened 

 sufficiently it was removed and the different bones were taken up and 

 thoroughly cleaned and fitted in their proper positions as indicated 

 by the respective depressions made by each on the surface of the 

 plaster bed. When all had been thus cleaned and replaced the photo- 

 graph reproduced in plate XX. was taken, showing the relative posi- 

 tion of the different elements from the dorsal or lower side of the fore- 

 arm and manus as they lay imbedded in the shale. In this manner we 

 have preserved the complete record of this limb and foot from the 

 time of its discovery until its final preparation in the laboratory. No 

 single fact has been lost which would aid us in a correct interpreta- 

 tion of the structure and arrangement of the different elements in the 

 fore-limb and manus of this particular type of dinosaur. To some the 

 careful methods thus detailed may appear as superfluous, but I am 

 convinced that they are not only desirable, but absolutely necessary, if 

 we are ever to arrive at an exact and satisfactory understanding of the 

 skeletal structures in the Dinosauria, where articular surfaces are in 

 most cases so poorly defined as to afford little evidence concerning 

 the exact position of bones found isolated, or detached and misplaced 

 through careless or indifferent field and laboratory methods. It is 

 impossible to attach too much importance or give too great credit to 

 Mr. Gilmore for the appreciation, judgment, and skill shown in col- 

 lecting and packing this skeleton, while the ingenuity of Mr. A. S. 

 Coggeshall in devising and improving laboratory methods, whereby 

 these heavy and exceedingly fragile bones are readily cleaned and 

 hardened so as to permit of being safely handled, is deserving of the 

 greatest praise. 



Description of the Limb. 



The Humerus. — The shaft of this bone is much constricted, while 

 the extremities are greatly expanded transversely, the proximal to a 

 ranch greater extent than the distal. There is a very prominent del- 

 toid ridge extending along the anterior external border from the proxi- 

 mal end throughout one-half the length of the bone. Between the 

 ridge and the inner margin there is on the anterior surface a rather 

 deep basin, subtriangular in outline, bounded above by the anterior 

 border of the slightly thickened broad proximal end, and externally 

 and internally by the deltoid ridge and internal lateral margins, which 

 converge inferiorly where the shaft becomes much restricted. The 

 proximal end has the transverse diameter much expanded while the 



