DISCOVERY OF THE TITANOTHERES AND ORIGINAL DESCRIPTIONS 



203 



Mauvais Terre, on the White River, one of the western confluents 

 of the Missouri, about 150 miles south of St. Pierre, and 60 

 east of the Black Hills, at a point which would very nearly 



The fifth and sixth molars (first and second true molars) re- 

 semble the one described, except that they want the third lobe, 

 and the dentine area on the crown of each lobe is much larger. 



Figure 157. — "Vertical view of the posterior tooth belonging to the lower jaw of 

 Mr. Prout's Palaeotherium" 

 After Prout, 1846. Natural size. 



The sixth is 33^ inches from front to posterior side. The 

 posterior lobe is 2 inches from the outer to the inner surface 

 and 1% inches long in the line of the jaw. The whole distance 

 on the jaw occupied by the three teeth is 11 inches. In the 



correspond with the intersection of latitude 43" with longitude 

 26° west of Washington. 



The Baculites and the Inoceramus which accompanied it and 

 which I at first supposed belonged to the same locality were 

 found in another formation — probably the Cretaceous- 

 distant about 100 miles, and included in the Grande 

 Detour or Great Bend of the Missouri River. 



This fossil bone is a fragment of the inferior maxillary 

 of the left side, consisting of the posterior part of the 

 bone, together with the last three molar teeth. The 

 ramus is much fractured and presents an irregular sur- 

 face; yet the general direction of its outline may be 

 made out. The length of this fragment is 15 inches, 

 its depth from the liighest point of the ramus (a) to 

 the lowest (h) is 9K inches: it narrows regularly forward 

 so as to measure only 3}4 inches from the lower sur- 

 face of the bone at (d) to the alveolar process of the 

 antepenultimate tooth at (c). The inner surface of the 

 bone is more uniform, being marked merely by depres- 

 sions for the attachment of muscles. The alveolar por- 

 tion is here very prominent and well rounded, the teeth 

 being planted more than an inch from a vertical line which 

 is tangential to the inner surface of the bone. It is 

 covered in places with a concretionary matter which 

 could not be removed without injury to the specimen; on 

 analysis, this was found to consist chiefly of carbonate of 

 lime, with some alumina, and a small proportion of silex. 

 The last molar tooth has the three lobes of the Pa- 

 laeotheria, as shown in Figure 2. The inner surface is 

 nearly smooth and flat and shows no trace of lobes. 

 The size of the tooth from posterior to anterior sides is 4}/^ 

 inches, of which 1^ inches belong to the anterior lobe, the 

 same to the middle, and 134 inches to the posterior. In 

 an upper view the two larger lobes have a deltoid form, 

 with the sides somewhat convex, and a rounded outer 

 angle. The thickness through from the outer to the op- 

 posite side is 15^ inches. The enamel of the inner side 

 folds over the surface, covering nearly a semicircular space 

 and leaving between it and the edge of the posterior en- 

 amel a subcrescent-shaped space (deltoido-lunate) of den- 

 tine, somewhat concave, which is nearly seven-eighths of 

 an inch broad at its widest part. These crescent-shaped Figure 158. — Original figures of Prout's "gigantic Palaeotherium," the 

 areas of the two lobes are connected by a continuous tract first titanothere discovered 



of dentine, nearly IJ^ lines wide at the narrowest part; 

 and the same tract continues from the middle lobe to the 

 posterior; upon the latter it does not widen over the in- 

 terior, as the reflexed inner enamel covers the whole of the crown, 

 excepting a narrow space adjoining the posterior enamel. The 

 prominent points of the crown between the lobes project about 

 half an inch; and probably much more in the perfect tooth. 



After Prout, 1847. A, "Fragment of the inferior maiillary of tlie left side," one-fourth natural 

 size; B, last lower molar on the left side, four-fLIths natural size. 



largest Palaeotherium hitherto described, the P. magnum, the 

 same teeth occupy a space scarcely one-third that of the Mis- 

 souri animal. 



St. Louis, December 10, 1846. 



