1870. ^^"^ [Cope. 



the Dicynodon rosmarus, Cope, and RhaMo'peUx longkpinu, Cope. The 

 latter he had fomierly suspected to be a Pterosaurian, bat he tliought it 

 more likely that it would turn out to be a Rhynchocephalian reptile. 



lEe called attention to four remarkable vertebrae from the Cretaceous 

 green sand of New Jersey, which were characterized by the possession of 

 enormous pneumatic foramina. The articular extremities of the extremi- 

 ties were rugose, and with scarcely any dense layer, so that they probably 

 belonged to an immature animal, and were to be referred to the sacral or 

 l.umbar regions. If they belonged to the latter, they indicated a coossifi- 

 cation similar to that seen in many birds. That they were not dorsals 

 is indicated by the lack of capitular articulations. The pneumatic foram- 

 ina occupied half of the centrum along its middle, leaving abutments fore 

 and aft, for the support of the neural arch, which was lost in each one. 

 There were no diapophyses. The neural canal presented a deepening and 

 compression at the middle of the centrum, and a rising and expansion 

 near the articulations. Centra much compressed medially, as well as 

 contracted upwards ; articular extremity subtriangular, witli rounded 

 angles and notch for neural canal one-third its vertical diameter. Can- 

 cellous tissue, coarse, but much finer than in Lselaps ; the dense layer thin. 

 The total length of the four, is seventeen and a half inches, the shortest 

 measuring four ; the otiier three, four and a half inches in length. The 

 complete number of six would have measured six inches in length. 



These vertebrae had been described as the sacrals of a young Hadro- 

 saurus by Leidy (Cretaceous Reptiles, XT. S., p. 100), but there are several 

 reasons for dissenting from this conclusion. The pneumatic foramina of 

 the sacral nerves, which, however, in known Reptiles and Birds, issue 

 between the neural arches, not beneath them, not only in the sacral, but in 

 the lumbar and other vertebrae. The reasons for questioning their perti- 

 nence to Hadrosaurus were, first : the genus Megadactylus presents 

 similar lai'ge pneumatic foramina, and they occur in both the caudal and 

 lumbar vertebrae ; the lumbar and caudal vertebrae of two species of 

 Hadrosaurus are known, and do not present any pneumatic foramina 

 whatever, which would scarcely be the case were the present vertebraB 

 sacrals of Hadrosaurus. Second : they form too long a series for the 

 known ilium of Hadrosaurus. From the approximation of the facets for 

 the sacral diapophyses in the type specimens of H. foulkei, it would ap- 

 pear that those vertebrae had somewhat the shortened form of the caudals. 

 Yet the j^resent animal appears to be a young one. Third : the structure 

 is in several respects more Megalosaurian than Iguanodontine. Thus the 

 alternate enlargement and contraction of the neural canal is seen in Palseo- 

 saurus and Clepsysaurus ; the neural arches appear to have alternated 

 above the articulations of the centra. The pneumatic foramina exist in 

 Lselaps, but of reduced dimensions. 



In respect to the presence of the foramina just mentioned, there is a 



resemblance to the Ornithopsis hulkei, recently discovered by Seeley, 



though here the comparison ends. In that form the cancellous texture 



of the centrum is extremely open and light, and composed "of enormous 



A. p. s. — VOL. xr. — 78e 



