594 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



lous recurved short limb of the bone, which thus becomes a horn-like 

 projection directed upward and forward at the base of the muzzle. This 

 may be considered in connection with the rising projection of the supra- 

 occipital bone, and with the fact that this short limb is entirely filled 

 with moderately coarse cellular tissue. As to bone No. 2, its sheath- 

 like portion may be parasphenoid, and the axial part presphenoid or 

 sphenoidal rostrum ; or the former may be the vomer, and the latter 

 the septum nasi, or basitrabecular. 



From the preceding, it is evident that the only comparisons which 

 throw any light on the probable positions of these bones are those made 

 with cranial elements of Birds. 



Bone J^o. 3 was found in contact with !N"o. 2. It is flat and subpar- 

 allelogrammic in shape. One side (the thickest) is excavated by a reg- 

 ular arch, with smooth free border at right angles to the other surfaces ; 

 a part of the opposite side exhibits a free narrow edge. All the other 

 borders are sutural, generally partly squamosal, without serratare or 

 roughness. This bone is lateral, and the segment of a circle may be a 

 portion of the orbit. There are several other bones belonging to this 

 series, but their description is postponed until their identification is prac- 

 ticable. 'So elements of the skeleton not cranial were found, excepting 

 a rib, a humerus, and a portion of the transverse border of the epister- 

 num. The latter resembles the corresponding piece in the Monoclonius 

 crassns Cope;* and a similar fragment of large size was found with the 

 remains of the Agathaumas sylvestre in Wyoming. 



2. Mandibles of herbivorous JD'mosauria. — Mandibular rami of numer- 

 ous herbivorous Dinosauria were found by the expedition, five of which 

 are especially instructive. Two of them are occupied with teeth of 

 Diclonius ; close to another a tooth of Diclonius pentagonus] was found ; 

 and near to another a tooth of Dysganus haydenianusX occurred. 



The first ramus I will notice was found by my assistant, Charles H. 

 Sternberg, who did not procure any teeth in connection with it. It is 

 the dentary bone of the right side, without its inner wall, so that 

 the alveoli are exposed as to their outer halves from the fundus to 

 the mouth. These represent closely placed, parallel, vertical grooves, 

 whose basal portion turns inward to continue upward again on the 

 inner wall. The space thus inclosed is filled with vertical columns 

 of teeth, which are not separated by transverse septa, bjit which, 

 are kept in place as they rise in the process of growth and pro- 

 trusion by the grooves just described. In the ramus in question, this 

 magazine could not have contained less than one hundred and eighty 

 teeth, perhaps more; so that the total number contained in the mouth 

 of this Saurian must have been at the least seven hundred and twenty. 

 In the distal portion of the jaw, the tooth-grooves are not so deep as 



* See Proc. Acad. Nat. Sci. Phila., 1876, p. 251. 

 t See Proc. Acad. Nat. Sci. Phila., 1876, p. 256. 

 X See Proc. Acad. Nat. Sci. Phila., 1876, p. 253. 



