SYSTEMATIC REVISION 6l 



shaft. There are well-developed ect- and entepicondylar processes, but no 

 entepicondylar foramen. 



"The radius and ulna are well developed, but the articular ends do not 

 show particular characters. The proximal and distal ends of both bones are 

 rather widely expanded. 



" The foot: There are six of the carpal elements preserved, seemingly 

 in position. Between the distal ends of the bones is a small intermedium; 

 at the distal end of each is a larger element in the position of the radiale and 

 ulnare. The foot is somewhat turned so that the bone which lies at the end 

 of the ulna may be either the ulnare or the centrale 2. Below the inter- 

 medium is a good-sized bone, the centrale i. The radial digit is relatively 

 long, and there is a stout metacarpal and three phalanges. It is not cer- 

 tain that the last phalanx is the terminal one, as the end of the digit is 

 obscured by matrix. The other digits can not be exposed without injuring 

 the specimen. 



" The vertebral column: There are lo anterior dorsal vertebrae preserved. 

 The anterior six have the dermal plates preserved in position; the posterior 

 four have lost them. The centra of the vertebrae can not be made out, but 

 the neural arches are all free and there is little doubt that che general form 

 is similar to that of Trimerorhachis. There are well-developed anterior and 

 posterior zygapophyses, and from the base of the posterior one a narrow, 

 winglike process extends downward and outward for the head of the rib. This 

 process was attached solely to the neural arch. The neural spines are 

 stout and strong with the apex expanded and rugose. The expansion of the 

 apex of che spine in the posterior vertebra is more nearly circular, but even 

 here the lateral edges are more extended than the fore and aft edges. In 

 the anterior vertebra the sides become widely expanded, the projections 

 extending outward and downward and meeting above in an angle, like an 

 inverted V. 



"Each of the anterior six vertebrae has the neural spine overlain by a 

 single dermal plate in the form of an inverted V closely conforming to the 

 apex of the spine and closely applied to it. The two sides of the plate meet in 

 an angle of 1 20° to 130°, but there is no median ridge nor any trace of a suture 

 to indicate that the plates were originally separate. The plates overlap each 

 other from before backward, and did not extend laterally far beyond the 

 extension of the neural spine; the upper surface is rugose with deep pittings. 

 There is no trace of any lateral plates overlying the ribs, and the condition 

 of the specimen is such that, if plates had existed, they would very likely 

 have been preserved. The distal ends of the scapula and the cleithrum lie 

 under the edges of the dermal plates, and it is likely that in life they nearly 

 touched the edges of the neural spines. 



"The ribs attached to the vertebrae have a slender, single head, but 

 about a centimeter below the proximal end there is developed a thin, trian- 

 gular process which extends backwards over the next following rib, and the 

 point even reaches nearly to the second rib following. Below this process 

 the ribs are flattened for some distance, but gradually assume the rounded 

 form again. In more posterior ribs, perhaps posterior dorsals, the head 

 of the rib is widely expanded and thin; it contracts rapidly, and about a 

 centimeter below the head there is given off a process to the rear, as in the 

 anterior ribs, but now the process is very slender and slants inward as well 

 as backward. The rib is flattened proximally, more rounded distally. 



