1 2'2-B 



THE EXTINCT BATRACHIA, REPTILIA 



lar form, but the extremities are plane. The posterior basis of the neural arch is on the 

 posterior third of the upper surface, and the anterior end has evidently supported its an- 

 terior part. They leave the median third of the canal open laterally, its median surface 

 passing into the external over a lateral shoulder. The arch probably hridged over this 

 interval. The chevron bone is long and wide, and with thin walls. A second caudal ex- 

 hibits similar characters. Two adjacent caudals in the same piece of matrix exhibit 

 shorter, deeper centra, with strongly concave inferior surfaces, which are separated from 

 the laterals by an obtuse longitudinal angle. Articular faces concave, forming vertical 

 ovals truncate below. The chevron bones are narrower, directed backwards, and of very 

 light construction. The neurapophyscs present the singular character indicated above. 

 Their contact with the centrum is anterior and posterior only, their basis being excavated 

 upwards into a regular arch, whose margins flare out a little. This remarkable structure 

 is only paralleled in the sacrum of other Dinosauria, where the nerves destined for the 

 sacral plexus, issue through huge foramina in the bases of the ncurapophyses. Here the 

 structure is continued on the caudals, and evidently for a very different purpose. The 

 neural arch has a high longitudinal carina, which is continued in the neural spine. It is 

 concave on each side between the zygapophyses. The posterior zygapophyses stand above 

 an intervertebral space, and the narrow neural spine rises above them, as is usual in Dino- 

 sauria. The zygapophysial faces make about an angle of 45°. A distal caudal is slender, 

 sub-cylindric, and with low neural arch. 



The rigid anterior foot displays five digits, though one of them opposite the ex- 

 tremity of the ulna, was very short. The phalanges are, from without, \ — 3 — 4 — 3—2; 

 they are short and stout, the ungues short, deep, much curved and compressed. That of 

 the interior digit is the largest ; the inner edge is rounded, the superior broad and slightly 

 flattened. At the middle of its length, a shallow groove near the dorsal outline begins to 

 contract to a sharply defined, narrow groove, which continues to the end of the claw. The 

 trochlear faces are well distinguished. The phalanges are stout and with a marked liga- 

 mentous pit on each side distally. The metacarpals of the two middle digits arc; slender 

 and twice as long as the adjacent phalanges ; that of the outer digit is one-third shorter, and 

 that of the inner, one-half shorter than the median. The fourth metatarsus is longer than 

 the external, hut much more slender than any other. This finger was shorter than the 

 third, and probably possessed three phalanges ; portions of two are preserved, and the 

 most distal is not ungual. 



The extremity of the ulna larger than that of the radius and rather more expanded. 

 Both bones of the fore arm arc very pneumatic, and oval in section. 



The femur is represented by both extremities with shaft adjacent, and that part of the 

 shaft supporting the third trochanter. It is peculiar in presenting a combination of char- 



i 



