E. L. Troxell — Palctolagiis, an Extinct Hare. 345 



sponds most closely to the large maxillary just described; 

 the large size of the three teeth remaining, P3.4 Mj, and 

 the heavy bands of enamel appear to be typical of P. tur- 

 gidus. Figure 6 shows a similar type of dentition, but of 

 a smaller animal. In both of these, one sees the cylin- 

 drical form of P3 with its smoothly infolded enamel and 

 the lobes of the molariform teeth entirely separated 

 except for a narrow bridge of enamel continuous with the 

 inner border. 



Two specimens, shown in figures 7 and 8, are of uncer- 

 tain identification — may, in fact, represent a new species 

 of rabbit — but because the evidence is not conclusive, and 

 further because they are large, they are grouped with 

 P. turgidus. The first, much younger and smaller, has 

 a more complex folding of the enamel of P3. Both show 

 the more pointed, conical form of this tooth unworn, the 

 intricate enamel foldings on the anterior side of the 

 second lobe of Mi, the third small lobe posterior on the 

 three intermediate teeth, and the apparent separation of 

 their main lobes — all characters of youth. 



This very large species exceeds in size the largest 

 modern hare in the Museum Osteological Collection, one 

 whose skull measures 91 mm. in length. 



Palceolagus haydeni Cope. 



Figs. 1, 2, 9-20. 



Several views are here shown (figs. 9-16) illustrating 

 the results of wear and also some slight individual varia- 

 tions, in different specimens of P. haydeni Cope. In this 

 species the upper jaw has three deciduous premolars, in 

 the lower there are two. 



The first specimen (fig. 9) shows the deciduous teeth, 

 three in number, slightly worn, standing alongside the 

 true molars. Molar 1 is somewhat worn, but 2 and 3 are 

 entirely untouched. The specimen shown in figure 10 has 

 lost the milk teeth with the exception of a smaU fragment 

 of Dp^. P^ is coming in beneath it. P^-* are fully cut, 

 but unworn. ■ M^ is well worn, M^ not enough to obliterate 

 the irregular outer enamel folds, M^ is still unworn. 



Specimen No. 10374 (fig. 11), partly due to wear, partly 

 to individual variation, shows a greater complication of 

 enamel. The technique of drawing the P^ gives the out- 

 line of enamel areas rather than the full enamel band. 

 The right maxillary (fig. 12) shows the first and last of 

 the series of teeth but little worn; P^-* M^-^ have worn to 



