Ondthosaurian Genus Ornithoclieirus. 551 



exhibits the raised and roughened surface for the biceps 

 tendon in a greater degree than any of the others on this 

 tablet. 



Tablet J. a. 11. The seven specimens on this tablet are 

 the proximal ends of ulnae. No. 1 is the proximal end of a 

 right ulna figured by Seeley, pi. ii. fig. 8 [loc. cit.), as the 

 proximal end of radius. It is much smaller, but similar to 

 Oniithodesiuus latidens, with the central transverse ridge on 

 the articular surface not so highly developed. This ridge 

 and the margins of the bone on the postaxial side are worn 

 away. The strong longitudinal ridge on the centre of the 

 ventral surface of the shaft is also destroyed, but its base is 

 well seen. A pneumatic foramen occurs, covered by a 

 small daub of matrix, near the articular surface, ventral side, 

 as in Ornithodesmus latidens. 



Nos. 2, 3, 4, 5, 6 all have the median vertical ridge on the 

 anterior surface of the shaft. All are close to no, 1, and thus 

 near to Ornithodesmus, but the ridges, processes, and articular 

 characters are either in an incipient or degraded state. 

 No. 5 has lost the median area of the articulation in such a 

 manner that it appears at first sight to be a basin-shaped 

 depression, whereas a closer examination proves that it is 

 due to wear. The pneumatic foramen is not seen in nos. 2-6, 

 for the same reason. 



No. 7, the proximal end of the right ulna, figured by 

 Seeley, pi. ii. fig. 7 {loc. cit.), is remarkably different from 

 the other six examples on this tablet. The only articular 

 surface preserved is on the preaxial side. It is slightly 

 convex and looks anteriorly. The dorsal surface and post- 

 axial border are destroyed. There is no pneumatic foramen 

 on the portion preserved. The great peculiarity of this 

 specimen is on the ventral surface, where the bone is concave, 

 with an elongated and deep pit (no foramen) for the biceps 

 tendon near the postaxial border. This is well seen in the 

 figure. The other pits observed are not natural, but the 

 borings of some organism. 



Distal end. 



Tablet J. a. 10, 1-10. There are eleven examples on this 

 tablet, the eleventh probably added since ' Ornithosauria * 

 was published. They are the distal ends of ulnse, and not 

 " radii.''' Nos. 1, 2, and 9 are similar in character, no. 2 is 

 the best specimen and figured by Seeley, pi. iii. fig. 1 (/oc. 

 cit.). On the ujajor portion of the dorsal surface, towards 

 the preaxial side, there is the flattened surface, against which 



