. The Ceratopsia. Ceratopsia. 78 THE CERATOPSIA. the same skeleton, though with a query. It differs little from the same bone in Agathaumas, except in its smaller size. It is proportionally longer and more slender in the present genus. SS Fig. 82.—A, Inferior view of right ilium (No. 3998? American Museum of Natural History) of Monoclonius crassus Cope; B, superior view of same, a. Anterior extremity; p, posterior; is, ischiac peduncle; pb, pubic peduncle; ss, surface for contact with sacrum. One-eighth natural size. and has the deflected external margin posterior to the ischiac peduncle more
. The Ceratopsia. Ceratopsia. 78 THE CERATOPSIA. the same skeleton, though with a query. It differs little from the same bone in Agathaumas, except in its smaller size. It is proportionally longer and more slender in the present genus. SS Fig. 82.—A, Inferior view of right ilium (No. 3998? American Museum of Natural History) of Monoclonius crassus Cope; B, superior view of same, a. Anterior extremity; p, posterior; is, ischiac peduncle; pb, pubic peduncle; ss, surface for contact with sacrum. One-eighth natural size. and has the deflected external margin posterior to the ischiac peduncle more marked and pro- duced into a somewhat angular prominence. The extreme ante- rior end of the blade is wanting, but otherwise the bone is essen- tially complete. Superior and inferior views of this ilium are given here in fig. 82. I have been unable to detect any portion of either pubis among the collections from the Judith River beds. There is a left ischium nearly complete, but lacking the extremity of the anterior process with the articular surface for the pubis and the extreme distal end of the shaft. This agrees very well in size and general characters with the other material that has been referred by Cope to M. crassus. I there- fore describe and figure it in this connection. In general form the ischium in the Ceratopsia is not very unlike a rib, and after a casual glance it might be mistaken for one of those elements. More careful study, however, will at once reveal its identity. Proximally it presents a moderately expanded subcircular articulation for contact with the ischiac peduncle of the ilium. Just below this it sends forward a rather slender process for articulation with the pubis. The extremity of this is wanting in the present specimen. The shaft of the ischium. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble th
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