G. F. Eaton — Characters of Pteranodon. 319 



eight vertebrae anchylosed to form the notarium, and four free 

 dorsals intervening between the notarium and the sacrum. 



Professor Williston has been at considerable pains to dem- 

 onstrate the number of cervical vertebrae in Pteranodon and 

 Nyctosaurus, and it is from him I quote :* " If, however, we 

 consider that vertebra which bears the first rib articulating 

 with the sternum to be the first dorsal, then I believe that the 

 prevailing number of cervicals in pterodactyls is eight. 



" From the foregoing, then, it seems assured that there is a 

 free, short vertebra in front of the notarium, in both Pteran- 

 odon and Nyctosaurus, bearing a free, small rib, which does 

 not unite with the sternum. This vertebra is the eighth cer- 

 vical, and is probably present in all pterodactyls." 



Following the atlas and axis are five vertebrae with long 

 centra, then two vertebrae with short centra, making nine cer- 

 vicals in all. Plate XX, figures 2 y 3, and 4, show the seventh, 

 eighth, and ninth vertebrae in their correct sequence, the long- 

 est of the three being the seventh. As there is no doubt that 

 the seventh is the most posterior of the long-bodied cervicals, 

 it is here only necessary to illustrate and call attention to the 

 last three cervicals, and to state that they were preserved in 

 their normal arrangement and that the ninth was in contact 

 with the first true dorsal or notarial vertebra, i. e., the first 

 vertebra connected by ribs with the sternum. I hope to show 

 later that Professor Williston is right in supposing that Pteran- 

 odon and Nyctosaurus have the same cervical formula. The 

 number of cervicals in Pteranodon, however, is nine, and not 

 eight as formerly supposed. Fortunately, the material in the 

 Yale University Museum satisfactorily decides this mooted 

 question. 



In describing the specimen of Nyctosaurus upon which 

 Professor Williston bases his calculation of cervical vertebrae 

 (Osteology of Nyctosaurus), he says that the eighth cervical lay 

 "close to the first notarial vertebra, and near the presternal 

 process of the sacrum," from which statement I must suppose 

 his evidence less satisfactory than my own. 



The four free dorsals which follow the notarium are shown 

 in their normal sequence in figures 5, 6, 7, and 8, of Plate XX. 

 Unlike the eight notarial vertebrae, these four were probably 

 capable of slight motion. This is indicated by the character 

 of the articular facets of the zygapophyses and of the ends of 

 the centra. The figures correctly show transverse processes 

 terminating in facets for the support of single-headed ribs. 

 Like all the vertebrae in the entire vertebral column, so far as 

 observed, these four free dorsals are procoelous. 



* On the Osteology of Nyctosaurus, Field Columbian Museum, Publication 

 78, pp. 127, 129, June 1, 1903. 



