U. S. GEOLOGICAL SURVEY 



MONOGRAPH 55 PLATE LXII 



UPPER AND LOWER PREMOLARS OF LIMNOHYOPS AND PALAEOSYOPS 



Drawings by E. S. Chriilman. (See pp. 312, 314.) Natural size. A-K, External (lateral) views of the upper premolars, show^ing 

 various ^ages in the separation of the cingulum from the edloloph; L-O, internal (medial) views of the low^er premolarSj 

 showing various ^agcs in the evolution of p2, ps. A, Limnohyops prisctis, type (Am. Mus. 11687), Gristly Buttes We^, 

 Bridger Basin, Wyo., level Bridger B 2, p^-pS drawing reversed. B, L. mo-noconusl (Am. Mus. 5102), Cotton^vood Creek, 

 Bridger Basin, Wyo., level Bridger B, p--p*, drawing reversed. C, L. laticeps, type (Yale Mus. 11000), Bridger formation, 

 level?, p3, p^, drawing reversed. D, Palaeosyops -major, neotype (Am. Mus. 12182), middle of Cotton\vood Creek, Bridger 

 Basin, Wyo., level Bridger B 3, p^-p^ drawing reversed. E, P. paludosus, one of the cotypcs (Nat. Mus. 762), level Bridger 

 B(?) 1-2, p<. F, Palaeosyops sp. (Am. Mus. 2361), south of Hayrack Mountain, Washakie Basin, Wyo., level Washakie A, 

 p2-p*- G, P. major (Am. Mus. 12182, same as D), p^, drawing reversed. H, P. rohu^us (Am. Mus. 1558), Twin Buttes, 

 Bridger Basin, Wyo., level Bridger C or D, p^, drawing reversed. I, P. leidyi (Princeton Mus. 10009), level Bridger C or D, 

 pi-p^, dra^ving reversed. J, P. rohu^us (Am. Mus. 1554), Henrys Fork, Bridger Basin, Wyo., level Bridger C(?) or D, p^-pS 

 drawing reversed. K, P. grangeri, type (Am. Mus. 12189), Twin Buttes, Bridger Basin, Wyo., 200 feet below red stratum, 

 level Bridger C 1, p'-pS draw^ing reversed. L, L. priscus (Am. Mus. 11688), Grizzly Buttes Bail, Bridger Basin, Wyo., level 

 Bridger B 2, p2-pj, draw^ing reversed. M, P. paludosus (Am. Mus. 11680), Little Dry Creek, Bridger Basin, Wyo., level 

 Bridger B 1, p2-p4, drawing reversed. N, P. major (Am. Mus. 12181), middle of Cottonw^ood Creek, Bridger Basin, Wyo., 

 level Bridger B 3, p2-pi, drawing reversed. O, P. leidyi (Am. Mus. 12200), Henrys Fork, Lone Tree, 50 feet below white 

 ^ratum, level Bridger C 1, p2-p4, drawing i 



