130 



Wg have additional species from — 



North Carolina (Mosasaurus) ■ 1 



Mississippi (Platecarpus) 1 



Nebraska (Mosasaurus) 1 



Making, with the others from — 



New Jersey 15 



Alabama .• 7 



Kansas 26 



A total of '. 51 



Of these, I am not acquainted with any species which extends its range 



into two of the areas above named ; while some of these districts possess 



peculiar genera. It is, nevertheless, premature to draw any conclusions as to 



geographical range, as most of the species are known as yet from but few 



specimens. 



HistorT/. 



The knowledge of the structure of the animals of this order has been 



due, almost exclusively, to the labors of three paleontologists, viz, Georges 



Cuvier, Prof 0. C. Marsh, and the writer. Cuvier determined the characters 



of the dentition, and of the anterior regions of the skull, and of the vertebral 



column. Professor Groldfuss added little to this beyond the description 



of the parieto-quadrate and postorbito-malar arches. The writer ascertained 



the structure of the posterior part of the skull, including the walls of the 



brain-case, the suspensorial apparatus, the pterygoid and palatine bones, and 



the median hinge of the lower jaw ; also, of the scapular arch and fore and 



liind limbs, except the phalanges. On this basis, the determination of the 



affinities of the order was made. Professor Marsh determined, for the first 



time, the presence of hind limbs, and described the pelvic arch ; he also 



determined the relations of the phalanges of the fore limb, the presence 



of two small supernumerary cranial bones, and the probable existence 



of dermal scuta. 



CLIDASTES, Cope. 



Vertebral column exceedingly elongate, the vertebrse united by the 

 zygosphenal as well as the usual articulation ; the zygosphene elevated but 



