SYSTEMATIC REVISION 55 



The name D. articulatus was applied to the single specimen by mistake 

 in later publications. 



In 1896 Cope gave the description of Otocoelus testudineus: 



"The skull is short, wide, and flat, and the orbits are large and situated 

 in the auricular excavations. Surface roughly sculptured with small pits 

 and^ ridges. Malar and mandibular bones shallow. Teeth small, compressed 

 conic, smooth, and without serrations. Scapular arch without sculpture 

 of the inferior surface. Humerus with widely expanded head and narrow 

 shaft. Bands of carapace of moderate transverse extent and roughly sculp- 

 tured with pits and tubercles. Width between auditory meatuses, 74 mm.; 

 do. between orbits, 32 mm.; do. between auditory sinus and orbit, 16 mm.; 

 transverse diameter of orbit, 28 mm.; width of carapace, 80 mm.; length 

 of clavicle, 80 mm.; transverse width of head of humerus, 35 mm.; length 

 of femur, 67 mm. ; length of vertebral centrum, 10 mm. ; width of do., 19 mm. ; 

 width anterior rib distally, 11 mm." 



The species 0. mimeticus is mentioned but not described in this paper. 



A more extended description of the genus appeared in the "Proceedings 

 of the American Philosophical Society" for 1896, in the description of Oto- 

 coelus testudineus: 



"Muzzle very short and broadly rounded. Top of head between and 

 posterior to orbits flat. Orbits directed principally upwards. Intertym- 

 panic width 2.5 times interorbital width. Table of skull posterior to orbits 

 about as long as wide. Postorbital width (longitudinal) half as great as 

 interorbital width, which is equal to transverse diameter of orbit. Long 

 diameter of orbit obliquely directed outwards and forwards. Malar bar 

 narrow. Quadratojugal surface posteriorly overhanging border of mandible 

 a little, and these contracted to an apex overhanging angle of mandible 

 posteriorly. Mandibular angle undivided. The superior surfaces of the 

 skull have a strongly impressed honeycomb structure, the ridges between 

 the pits being frequently interrupted. The sculpture extends to the inferior 

 border of the mandible. The pits average 2 mm. in diameter. The sculp- 

 ture is present on the external surface of the posttympanic hook, where 

 the decurved border is concave. The median parts of the frontal and par- 

 ietal bones are smooth, but whether this is normal or is the result of weather- 

 ing I do not know. 



"The mandibular ramus presents, a short distance anterior to the 

 angle, a horizontal expansion with a convex border directed inwards and in 

 contact with the pterygoid. 



"The crowns of the teeth are acute and smooth. They overlap the 

 edge of the lower jaw and are separated by interspaces equal to their own 

 diameter. They are of quite small size. 



"The articular face of the humerus extends downwards on the inner 

 border of the head; perhaps it is restricted to this part of the latter. The 

 section of the shaft is semicircular. 



"The fragment which contains the vertebrae, hind leg, and carapace 

 does not form a fit with any fractured face of the mass containing the skull. 

 As, however, everything about the two blocks is harmonious, and as they 

 were found close together, I have no doubt of their pertinence to the same 

 skeleton. The second block is splic longitudinally, so that only one-half 

 of the carapace is preserved; but at the supposed proximal end enough of 

 the middle portion remains to include the two vertebrae already described. 



