NATURAL SCIENCES OF PHILADELPHIA. 405 



Trias in Europe, and the only living species is found in New 

 Zealand. Thus it would seem that a fragment of this fauna, so 

 ancient in the northern hemisphere and so remarkably preserved 

 in the southern, has been brought to light in Illinois. It must be 

 added, in reference to the geologic age of the fossils, that the 

 genus Diplodus, Ag., has not yet been discovered above the car- 

 boniferous ; and that one genus of the Bhynchocephalia belongs 

 to the Permian in Germany. We, therefore, await further mate- 

 rial before venturing a decision whether they belong to Triassic 

 or Permian time. 



Cricotus heleroclitus, Cope. 



Generic characters. This genus is indicated primarily by 

 caudal vertebne ; other parts of the skeleton found with it 

 probably belong to the same animal, so I describe them in this 

 connection, awaiting further discoveries to confirm or disprove 

 such reference. The pieces include parts of two femora of 

 ? tibia, ? ulna, metapodial and phalangeal bones, ribs, and other 

 pieces. 



The caudal vertebra best preserved is stout, discoidal in form, 

 and deeper than wide. It resembles in form that of an herbivorous 

 dinosaurian, but differs otherwise. The articular faces are deeply 

 concave, the posterior most strongly so ; and the middle is occu- 

 pied by a large foramen, whose diameter is about equal to that of 

 the centrum on each side of it. The lateral borders of the poste- 

 rior articular face are expanded backwards, and articulate with a 

 bevel of the corresponding edge of the anterior articular extremity. 

 In this wa} r the vertebra combines the mechanical relations of the 

 biconcave with the opisthocoelian structures. The neural arches 

 are narrow, and directed backwards ; their bases are firmly 

 coossified with the centrum ; no zygapophyses appear on the 

 portion of the neurapophyses preserved, and it is probable that 

 they were weak if existing. On the inferior surface of the centrum 

 two shallow pits occupy considerable space, and indicate the ex- 

 istence of large, free, chevron bones. No transverse processes. 

 In one vertebra the floor of the neural arch is deeply excavated ; 

 in the other it is plane, and marked with a median groove. 



Of the remaining bones it may be observed that the articular 

 faces were evidently capped by cartilage, and do not present the 

 smooth condyloid character common to so many reptiles. They 

 are, indeed, not so smooth as the dense layer of the shafts and 



