4© AMPHIBIA AND PISCES OF THE PERMIAN OF NORTH AMERICA 



superior surface. Th-? mucous grooves are distinct, but do not form a well- 

 defined lyra. There is a groove which is parallel to the anterior borders 

 of the orbit for a short distance, and which then turns forwards and then 

 inwards. The dermal ossification is distinguished from that of the maxillary- 

 bone by a squamosal suture. A mucous groove descends to it obliquely 

 forward from the superior quadrate region, and sends a branch at right 

 angles to its anterior extremity to a point posterior to the orbit. Of super- 

 ficial ossifications, the boundaries are difficult to determine, owing to the 

 obscurity of the sutures. Enough can be seen to demonstrate the presence 

 of supramaxillary, epiotic, and supraoccipital dermal bones. The nostrils 

 are large and well separated, and look upwards. 



"The teeth are acute and of subequal size; th^Ir superficial layer is 

 deeply inflected at the base. 



"The parasphenoid bone is wide posteriorly, but contracts abruptly and 

 extends forwards on the middle line. Owing to the crushing of a part of the 

 surface, I am unable to ascertain its anterior or vomerine suture. The basi- 

 facial axis bone is quite narrow and is edentulous. It is connected with the 

 superior cranial walls by a vertical osseous plate on each side, which may 

 represent alisphenoid, orbitosphenoid, and ethmoid. The palatopterygoid 

 arch is a longitudinally extended sigmoid, enclosing, with the axial elements, 

 an enormous, choanobrbital foramen. It extends from the middle line below 

 a short distance posterior to the position of the nostrils outwards, and fol- 

 lows closely the maxillary bone well posteriorly. It then turns inwards, 

 extending to the parasphenoid bone, with the wide portion of which it has 

 an extensive contact. It then turns outwards as pterygoid bone and, rapidly 

 narrowing, joins the inner distal extremity of the quadrate. It thus incloses 

 a foramen with the quadratojugal bone, which is much smaller than the 

 choanobrbital foramen. The posterior part of the inferior surface of the 

 bones of this arch, not including the slender pterygoid portion, is roughened 

 with hard nodules resembling teeth in material, and serving the purpose of 

 such organs. 



"Two rod-like bones extend outwards and backwards from the posterior 

 part of the parasphenoid and the basioccipital, which belong to the inferior 

 arches. The anterior is the larger and is bent backwards at an obtuse angle; 

 its proximal extremity is a truncate oval. This bone occupies the position 

 of the stapes. The second is extensively in contact with the basioccipital 

 by its proximal extremity. It is curved backwards at its distal third. The 

 occipital condyle is represented by a fish-like cotylus, which has a deep 

 notch at its superior border. 



"The mandible has a short, angular process, vertical by lateral compres- 

 sion. The symphysis is very short and the Meckelian cavity large and 

 completely inclosed. 



"The anterior, cervical vertebrae consist of the same elements as the dor- 

 sals. The intercentra of the second and third vertebrae support capitular 

 costal articulations, somewhat elevated above the surrounding level. The 

 pleurocentra do not support the ribs, but the neural arches terminate below 

 in diapophyses. There is a pleurocentrum in front of the second inter- 

 centrum, and above and in front of it a neurapophysis, which has no distinct 

 diapophysis. Its superior portion is a subacute process which is not in 

 contact with that of the other side, but is separated from it by a vertical 

 osseous plate, which is probably the neural spine of the second vertebra 



