Nodosaurus textilis Marsh. 105 



they have been thus restored (pi. III). The neural canal 

 shows a sacral dilatation reaching an apparent maximum 

 at the beginning of the primary sacrum, but it has by no 

 means the exaggerated development shown in Stego- 

 saurus. 



Ilia. — Both ilia are imperfect, but in a measure 

 supplement each other, so that except for the outline of 

 the anterior portion, especially its forward limitation 

 and its inner margin, the shape was probably as shown 

 in plates II and III. The ilia lie largely in the horizontal 

 plane except anteriorly and toward their outer margin, 

 the iliac crest, where they curve downward. Dorsally 

 their inner margin is continuous with the sacral diapo- 

 physes, which become more broadly wedge-shaped 

 posteriorly and have their apex directly inward. The 

 posterior extremity of the ilium is thickened, convex 

 below, mth a corresponding although much less 

 pronounced concavity above. The remainder of the 

 upper surface is relatively smooth, first concave and then 

 convex from the rear forward. There are, however, well 

 defined blood-vessel impressions indicating a close-fitting 

 corneous investment, but no trace of overlying armor 

 comparable to that over the sacrum. The iliac crest or 

 margin is somewhat undulating and in places is thick- 

 ened and rugose for muscle or tendinous attachment. 



Ventrally, the ilia show three rounded ridges diverging 

 from the acetabulum, flanked by four concavities of 

 varying extent, of which the greatest lies beneath the 

 whole anterior portion of the ilium. Behind this lies the 

 lateral depression just without and almost confluent mth 

 the acetabulum. This receives the great trochanter of 

 the femur. The acetabulum is large, almost perfectly 

 hemispherical, and w^as bounded in front by a well 

 developed pubic peduncle, the entire height of which is 

 not preserved. The ischiatic peduncle was much lower 

 and less well defined, but it also is ill preserved ; it had, 

 however, a rugose surface (pi. Ill, i). The inner margin 

 of the acetabulum was well developed and buttressed by 

 the three sacral ribs. 



Sacral armor (see also page 120.) — The dermal armor 

 over the pelvis, unlike that of either Polacanthiis or 

 Stegopelta, seems to have been confined to the sacral 

 region only, although it probably in part overlay the inner 

 margins of the ilia, and wdth them formed what Wieland 

 has called the lumbar-hip carapace. In both Polacanthus 



