Cope.] J--^ [May 15, 



anterior part, the superior costal surfaces rise between the carapacial 

 bands to the plane of the latter, forming a closer surface tlian poste- 

 riorly. 



This genus forms a remarkable example of homoplastic resemblance 

 to the rhachitomous genus Dissorhophus, which I described in the 

 American Naturalist for IS'ovember, 1890. The superficial resemblance 

 is very great, and it is only after an examination of the constitution of 

 the carapace that the difference of this part of the structure in the two 

 genera is observed. In the batrachian genus the ribs are free from and 

 not in contact with the carapace, and the inferior stratum of the latter 

 consists of the expanded neural spines. (See Plate X.) 



Char, specif. — Muzzle verj' short and In-oadly rounded. Top of head 

 between and posterior to orbits flat. Orbits directed principally up- 

 wards, lutertympanic 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 trans- 

 verse diameter of orbit. Long diameter of orbit obliquely directed out- 

 wards and forwards. Malar bar narrow. Quadratojugal surface i)os- 

 tei'iorly overhanging border of maudi])le 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 honej'comb sculpture, the ridges between the pits being fre- 

 quently interrupted. The sculpture extends to the inferior border of the 

 mandible. The pits average 2 mm. in diameter. The sculpture is 

 present on the external surface of the posttympanic hook, where the de- 

 curved border is concave. The median parts of the frontal and parie- 

 tal l)ones are smooth, but whether this is normal or is the result of 

 weathering I do not know. 



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

 a horizontal expansion with convex border directed inwards and in con- 

 tact 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 doAVnwards 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 vertebra^, hind leg and carapace, 

 does not fcn-m a fit with any fractured face of the mass containing the 

 skull. As, howcA'er, everytliing al)out tlie two l)locks is harmonious, 

 and as they were found close together, I have no doubt of their i)erti- 

 nence to the same skeleton. The second block is split longitudinally, so 

 that only one-half of the carainice is preserved; but at the supposed 

 proximal end enough of tlie middle portion remains to include the two 

 vertebne already described. A portion of one hind leg. including the 

 distal ])ar1 of tlie femur with tlic tibia and lihula. lie over tlie earapace 



