On the Osteology of Nyctosaurus. 127 



a proatlas, said by Zittel to occur in the pterodactyls, but of which there is 

 no other evidence in this specimen. Since the removal of this bone from 

 the matrix, it seems quite surely to be, rather, the anterior, median element 

 of the hyoidean apparatus. One view, which I take to be the superior, 

 is shown in PI. XLI, Fig. 6, three times the natural size, and, in Fig. 7 of 

 the same plate, is shown one of the articular extremities (a) from the side, 

 much more enlarged. The bone is nearly flat, with the pointed extremity 

 curved upward, and with the two articular extremities much more 

 massive than the remainder of the bone; they are also directed upward. 

 Each has a smooth, synovial articular surface, doubtless for the articula- 

 tion of the cylindrical rods. On the opposite surface, near the articula- 

 tions, there is a slight longitudinal ridge, and near the middle of the 

 bone on each side, there is an elongated, oval surface, apparently for 

 muscular attachment. The slender rods seem to agree quite with the 

 hyoidean bones of other pterodactyls, but I cannot find that the triangu- 

 lar bone has ever been described. 



VERTEBRAE. 



Seven has usually been accepted as the number of vertebrae in the 

 neck of pterodactyls. 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. Furbringer has already expressed the opinion that there are 

 eight vertebrae instead of seven:* "Falls die Patagiosaurier zum Theil 

 nur sieben Halswirbel besitzen, wie algemein behauptet wird, aber 

 meines Erachtens erst noch zu erweisen ist, so ware eventuell anzu- 

 nehmen, das dieselben durch eine geringgradige, kranial gerichtete 

 Wanderung der vorderen Extremitat ihren urspriinglich aus acht 

 Wirbeln bestehenden Hals um einen in das thorakale Gebiet uberge- 

 henden Wirbel verkurzten." He further expressed the opinion that 

 the vertebra which I had considered to be the first dorsal in Pteranodon 

 was really the eighth cervical. In a later paper I stated that the eighth 

 vertebra in the neck of Nyctosaurus was a functional cervical, though a 

 structural dorsal. ... I have usually assigned this vertebra to the dorsal 

 series because of its great structural differences from the anterior cervicals; 

 but these differences are scarcely greater than those of the last cervical in 

 the turtles. Owenf correctly located it in the neck. In his description 

 of this vertebra in Dimorphodon he says: " At the base of the neck or the 

 beginning of the back, the vertebrae suddenly decrease in length; the 

 hypapophysis disappears, or is represented only by a slight projection of 



* Jena. Zeitschr. f. Naturwissenchaft, vol. xxxiv, p. 665, 1900. 

 t Paleontograph. Soc, i860, p. 60. 



