PROBOSCIDEANS 351 



fied horn cores (plate 23, figure 1). There are two large calcanea and 

 other undetermined bones, probably of Ungulata. 



Proboscideans 

 elephants 



Elephas imperator. — Three elephants are indicated by the collections 

 from the Aftonian gravel pits. A large, slightly worn molar, shown on 

 plate 24 about three-sevenths natural size, has the massive proportions 

 and the coarse ribs which distinguish Elephas imperator* Leidy. This 

 ponderous, clumsy tooth is from the Peyton pit at Pisgah; it is 290 milli- 

 meters (about 11% inches) in length, 108 millimeters (4% inches) 

 across the grinding surface, and 265 millimeters (10% inches) high, 

 measured between two planes parallel to the grinding surface. The 

 enamel loops, corresponding to the longitudinal ridges on the lateral faces 

 of the tooth, vary in thickness and in the width of the intervening spaces, 

 but on the whole they are more constant in these respects than are those 

 of the tooth illustrated by Holmes 10 and Lucas 11 and which served to re- 

 establish Elephas imperator as a valid species. In some parts of the 

 Iowa specimen the ridges are fully an inch in width, the number in 10 

 inches ranging from 11 to 14, according to the part of the tooth selected 

 for measurement. Besides the large tooth from Pisgah, there is an im- 

 perfect lower jaw from the Cox pit at Missouri Valley (plate 25, figure 1) 

 which belongs to this species. In both rami the inner side of the alveolus 

 has been broken away, but the outer wall is intact and shows the broad, 

 vertical grooves corresponding to the wide ridges on the lateral face of 

 the tooth. These are of the same order of magnitude as the ridges of the 

 Pisgah tooth referred to Elephas imperator. A large femur to be noted 

 later probably belongs to this species. 



Elephas primigenius and E. columbi. — There are other and very differ- 

 ent elephant teeth in the Pleistocene collections of the University of Iowa 

 in which the number of ridges in 10 inches range from 20 to 25. The 

 exact horizon for some of these is not known, but there is one from the 

 Cox pit showing 20 folds or ridges in the space mentioned, and another 

 from the gravels at Denison showing 25. The specific relationship of 

 these admits of little doubt. Lucas, in the work cited, page 159, specifies 

 18 ridges in 10 inches as characteristic of Elephas columbi and 24 in the 

 same space as marking the molars of E. primigenius. Making the neces- 



10 William Henry Holmes : Flint implements and fossil remains from a sulphur spring 

 at Afton, Indian Territory. Report of U. S. National Museum for 1901, p. 244, plate 9. 



11 P. A. Lucas : Maryalnd Geological Survey, 1906. Pliocene and Pleistocene mam- 

 malia, p. 167, pi. xxxviii, fig. 2. 



