84 G. F. Eaton — Characters of Pteranodon. 



tionally upon the characters of Nyctodactylus when making 

 his restoration of Pteranodon. 



The Suspensorium. 



Another remarkable character of the skull of Pteranodon^ 

 which belongs apparently to Nyctodactylus also, is the articu- 

 lation of the mandibles with the quadrates. The distal end of 

 each quadrate has the form of a spiral groove, left-handed in 

 the right quadrate and right-handed in the left. The articular 

 elements of the mandibles have a reciprocal form. So jDerfect 

 is the mutual adjustment of these parts that, unless actual dis- 

 location took place, the act of opening the mouth must have 

 resulted either in a considerable widening of the lower 

 jaws posteriorly or in the forcing together of the quadrates. 

 Apparently the pterygoids and palatines serve as a rigid and 

 immovable support to the quadrates, a condition which would 

 render movement of the latter imjjossible. In such case an 

 expansion of the lower jaws is, in my judgment, the only way 

 by which the lateral motion caused by the spiral articula- 

 tion could be taken up mechanically ; and this in the face of 

 the seemingly inflexible mandibular symphysis and the thor- 

 ough union of the mandibular elements. 



The existing vertebrate offering the closest parallel in this 

 respect to Pteranodon is the Pelican. A careful inspection of 

 the suspensorium of this peculiar bird reveals a similar spiral 

 articulation between quadrates and mandibles, and it is recorded 

 that in the Pelican the act of opening the mouth results also 

 in the widening of the jaws posteriorly. There has been some 

 speculation in regard to the habits of the American Ptero- 

 dactyls, but no definite conclusions have yet been reached. 

 Possibly the mechanical similarity between the mandibular 

 suspensorium of the Pelican and that of Pteranodon is to be 

 received as evidence of the possession of a gular pouch by this 

 Pterdactyl as well as by the bird. 



Mr. Lucas has apparently arrived at the same conclusion 

 along another line of evidence. He says (loc. cit.) : "In the 

 peculiar shape of the lower, back jDortion of the beak there is 

 a suggestion of the former presence of a small pouch, like 

 that found in cormorants, and this would be in accord w^ith 

 the supposed fish-eating habits of Ornithostonia " {Pteranodon 

 Marsh). 



The Pelvis. 



A nearly perfect pelvis, recently worked out at the Yale 

 Museum, throws much light on the discussion of the charac- 

 ters of this important part of the skeleton of Pteranodon^ 

 which has not been thoroughlj^ understood and described by 



