7(1 \i:\V REPTILES AND BTEGGCEPHALIANS FROM 



DESCRIPTION OF ISOLATED BONES OF PAKASICHIAXS. 



Many isolated hones were found in the beds in Crosby County, Texas, and 

 a few in the Bad Lands west of San Jon, New Mexico. Some of these are described 

 and figured below: 



An iiiterclavicle (No. 7112, University of Michigan) found by Mr. Paul Miller 

 in the Bad hands "> miles west of San .Jon, New Mexico, resembles in general the inter- 

 clavicle <>f Myatriosuehua pUrnvroatris, figured by McGregor. 1 The blade is stouter and 



the articular faces for the clavicles are deeper and larger. The anterior portion is heavily 



rugose on the lower side, and the dividing septum between the two articular faces h 

 elevated and strong. The distal end is incomplete, but enough is preserved to show t hat 

 the whole bone was shorter and wider than in .1/. planirostrU. The upper face of the 

 blade is gently convex and covered by fine radiating lines in the posterior half. The 

 lower surface of the hone is gently convex in front, but the posterior half is nearly flat. 

 This portion is marked by rough, radiating rugosities imposed upon a sculpture of very 

 line lines. The whole bone is 216 nun. long as preserved, and could not have been a very 

 great deal longer when complete (fig. 27 a I. 



A second iiiterclavicle (No. 7313, University of Michigan) was found in the same 

 region; it is very imperfect, but indicates the presence of a very large animal, in which 

 the posterior extension of the interclavicle was much greater than in the one described 

 and figured above. 



There are five ilia and partially complete pelves (Nos. 7244, 7266, 7322, 7333, 

 7470), all in the University of Michigan collection. Four of these are so decidedly 

 different that they indicate the presence of different forms of at least specific value. 

 They are described separately below. 



No. 7322 is a perfect ilium from the right side, discovered in the breaks of Sand 



k, Crosby County, Texas. It is shown in figure 27 b; plate 13, figure a. The 

 anterior extension of the upper edge is somewhat elongated and down-curved: it extends 

 as far forward as the articulation of the lower anterior edge of the ilium with the pubis. 

 This hook-like extension is rather broad above, hut not nearly as broad as in some of the 

 other ilia. The lower edge of the posterior extension of the ilium extends forward at a 

 gentle angle to form the articulation with the ischium. The extreme posterior edge 

 of this slanting surface is curved inward, giving a broad posterior face inclined backward 

 and outward, 'the cotylusis very deep and the faces for the articulation with the ischium 

 and pubis meet at a gentle angle or on the surface of a broad curve. The upper edge 

 of the blade is moderately broad, anil the anterior face of the blade rises almost directly 

 from the upper edge of the cotvlus. The inner face i- somewhat water-worn and the 

 articulations for the sacral ribs are in part destroyed, hut it h apparent that they stood 

 very much lower upon the hone than in other specimens and that the whole blade of 

 the bone was more slender. 



No. 7211. also from Sand Creek, Crosby County, Texas, is very different in form 

 from the preceding (fig. 27 c; plate 13, fig. b). The anterior process of the blade of 

 the ilium i- very short, not reaching halfway to the articulation of the ilium with 

 the pubis. The extremity does not turn downward at all, hut is directed slightly upward 

 through its whole length. The upper edge of the blade is relatively thin and slightly 

 rugose on it > anterior face. 'I he whole blade is more than twice as thick as in the 

 preceding specimen, for on the inner side of the bone there i> a concave area looking 

 inward and upward before the articular faces for the sacral vertebra' begin. The posterior 

 process extends almost directly backward) from the articulation witli the ischium the 



1 McGregor, l II Memoin American Museum Natural History, vol. ix. pari n, fin. 9, 1906. 



