202 



nearly complete, of" one individual; by the tooth-bearing bones, palatine arch, 

 muzzle, and sclerotic bones, of a second ; by the tooth-bearing bones, witli fin 

 rays, of a third; and l)y many cranial bones, with vertebrae, of a fourth. 

 Three of these indivicUials had reached a larger size tlian those of the P. 

 molossus which have come under my observation,' and represent the largest 

 species of the Kansas Cretaceous. 



It differs from the P. molossus m the possession of three, and sometimes 

 four, premaxillary teeth. Three is the usual number, but one specimen 

 exhibits a minute fourth, which is present and still larger in another jaw. 

 As P. molossus may in like manner present a variation in the possession of a 

 third minute tooth, it is necessary to note otiier differences. While the pre- 

 maxillary and anterior portions of the maxillary have the same transverse depth 

 in the specimens of the two species, these elements are notably thinner and 

 lighter in P. molossus, so that the anterior condyle of tlie maxillary is much 

 narrower and smaller in it than in the P. lestrio. The depth of the maxillary 

 distal to its jjosterior condyle is also proportionately less in the P. ?nolossus. 

 The measurements of corresponding parts in these species and the P. mudaei 



may be compared as follows : 



Measuremfnts. 



p. moluntius. 1\ lestrio. P. mudjci. 



Depth of the premaxillary 0™. 0.)4 0"'.094 0"'. 070 



Depth of the maxillary bebinfl the posterior condyle .000 .065 .040 



Width of the auterior coud vie of the maxillary... .011 .016 ? 



Width of the maxillary behind the posterior condyle . Olli .018 .020 



In the specimen first enumerated, the first premaxillary tooth is very 

 large, the two others of moderate size. These are followctl by a long rugose 

 diastema before the maxillary teeth begin ; these are, one small, five large ; 

 twenty-two small, and eleven or twelve very small. Tlie mandibular teeth 

 are, one very large, one immense, one small, one medium, four small, eight 

 large, and two small — total, eighteen. The teeth are all sin.i[)]y round or oval 

 in section, and the external, probably cementum, layer is smooth. The max- 

 illary bone has two large superior proximal condyles, separated by a space; 

 the anterior is the narrower, and is directly behind the premaxillary condyle. 

 The anterior margin of the latter bone is very rugose. 



3Ica.iityemcnfs. 



M. 



Li!M};lli of the tooth-line of the npper jaw 0. 300 



Length of the tooth-liue of the premaxillary 0.0,58 



Depth of the premaxillarj« (axial) 0.09.5 



' See Proceedings of the American Philosophical Society (on the fishes of the Kansas Cretaceous), 

 J.muary, 167-2. 



