134 Field Columbian Museum — Geology, Vol. II. 



wanting. I suspect that the rib was single-headed here. Because of the 

 small size of this rib, the large size of the exapophyses, and the very free 

 union of the vertebra, as also because of the position of the notarium in 

 the specimen, apparently in articulation with the first tubercle of the 

 sternum, I feel confident that this vertebra does not articulate with 

 the sternum, and that it is a cervical. 



Plieninger, 1. c, considers the eighth shortened vertebra in Ptero- 

 dactylus as the first dorsal, because it bears a diapophysis. No rib was 

 preserved in his specimen, and he does not state whether there is- a 

 parapophysial process for the rib. If a rib was present, it was doubtless 

 small, since the next three pairs of ribs are found in place, and are 

 " besonders kraftig." The next three or four pairs are also strong. The 

 posterior ribs are slender. 



Dorsal vertebra. PI. XLI, Fig. i; PI. XLIII, Fig. 7. The three firmly 

 united vertebra? of the notarium, which are visible, lie with their ventral 

 side uppermost, directed a little obliquely toward the left side, and are 

 partly concealed beneath the sternum. The front end lies about ten 

 millimeters back of the front end of the presternal process of the sternum. 

 The first two centra are visible nearly wholly, the third only in part. The 

 centra are flat below, concave on the lateral margins. The first has a 

 concave cup margin, and on each side a stout parapophysis is continued 

 into a strong rib, without clear indications of sutural union. This ver- 

 tebra in the Kansas University specimen has the ribs free, and it was 

 itself separable from the following centrum through its suture; it is 

 figured in PI. XLIII, Fig. 7, and has already been described. The 

 parapophysis of the second notarial vertebra seems to be given off some- 

 what further back, and there are indications of its sutural union with the 

 rib about seven millimeters from the body. The rib is four millimeters in 

 width beyond its proximal part, and a length of about thirty millimeters 

 was preserved. A specimen of a notarial rib, probably the first, preserved 

 with the Kansas University specimen, has a length of forty-five millimeters 

 and a width of five. The corresponding rib in this specimen must have 

 been not less than fifty millimeters in length, and probably about sixty. 

 Whether the third vertebra bears similar anchylosed ribs in this specimen 

 cannot be said, as they are covered by the sternum, but since the third 

 vertebra in the Kansas University specimen has such, it is undoubtedly 

 also the case in this. The end of a flattened rib, about twenty-five 

 millimeters in length and three or four in width, is lying by the articular 

 margin of the sternum, and may belong to this vertebra. 



Lying in the axis of the notarium, a convex rim of a dorsal vertebra 

 has partly protruded through the thin sternum. This vertebra is doubt- 

 less either in direct articulation with its preceding vertebra, or but very 



