DISCOVERY OF THE TITANOTHERES AND ORIGINAL DESCRIPTIONS 



165 



Etymology. — laevis, levis, smooth, shining; dens, 

 tooth; apparently in allusion to the "smooth and 

 shining enamel." 



Present determination. — This is a valid species refer- 

 able to the genus Limnohyops. 



Limnohyus fontinalis Cope, 1873 



Cf. fPalaeosyops fontinalis Cope, this monograph, page 317. 



Original reference. — Pal. Bull. No. 11, "issued Jan- 

 uary 31, 1873"; Am. Philos. Soc. Proc, vol. 13, pp. 35, 

 36, 1873 (Cope, 1873.5). 



Subsequent references. — Cope, On the extinct Verte- 

 brata of the Eocene of Wyoming, observed by the 

 expedition of 1872: U. S. Geol. and Geog. Survey 

 Terr. (Hayden) Sixth Ann. Kept., p. 594, 1873 (Cope, 

 1873.6); Tertiary Vertebrata, p. 707, pi. 49, fig. 9; 

 pi. 50, fig. 4; pi. 58a, figs. 4, 5, 1884 [1885], (Cope, 

 1885.1). 



Type locality and geologic Tiorizon. — "Found by the 

 writer on a bluff on Green River, near the mouth of 

 the Big Sandy, Wyoming." ("Isolated patch lying 

 northeast of the badlands." Probably Eometarliinus- 

 Trogosus-Palaeosyops fontinalis zone (Bridger A).) 



Holotype. — A young, fragmentary skull (Cope col- 

 lection. Am. Mus. 5107, retaining dp*, m', - - 

 m^ of the right side. (See fig. 97.) 



Characters. — Cope writes: 



A small species agreeing with the P. paludosus 

 in the two interior cones of the last superior 

 molar. It is represented especially by a consider- 

 able part of the cranium of an individual in which 

 the last superior molar is not quite protruded, 

 but with the other molars and last premolar of 

 the permanent dentition in place. The enamel 

 of these teeth is in accordance with the age, delicately rugose, 

 and while the cingulum is present fore and aft, it is wanting 

 internally and externally. The anterior median tubercle is 

 present on all the true molars, and the bases of the acute inner 

 cones are in contact. The sagittal crest is truncate, and the 

 squamosal portion of the zygoma very stout. The nasal bones 

 are together very convex in transverse section. 



Palaeosyops diaconus Cope, 1873 



Cf. Palaeosyops robustus (Marsh), this monograph, page 331. 



Original reference. — Pal. Bull. No. 12, p. 4, "pub- 

 lished March 8, 1873" (Cope, 1873.1). 



Subsequent references. — Cope, On the extinct Verte- 

 brata of the Eocene of Wyoming observed by the 

 expedition of 1872: U. S. Geol. and Geog. Survey 

 Terr. (Hayden) Sixth Ann. Kept., p. 593, 1873 (Cope, 

 1873.6); Tertiary Vertebrata, p. 706, pi. 51, fig. 3, 

 1884 [1885] (Cope, 1885.1). 



Type locality and geologic horizon. — Henrys Fork of 

 Green River, Wyo.; Uintatherium- Manteoceras- Mesa- 

 tirhinus zone (Bridger C or D). 



Holotype. — "Represented by parts of the two 

 maxUlary bones, which present the crowns of the third 

 and fourth premolars, and of the second and third 

 true molars, with the bases of the other molars and 

 premolars." (Cope collection. Am. Mus. 5106.) 

 (See fig. 98.) 



Characters. — Cope writes: 



Belonging to the genus Palaeosyops as understood by Marsh — 

 that is, with two cones on the inner side of the last superior 

 molar. The species is as large as the Limnohyus major of 

 Leidy but differs in the relative proportions of the teeth. 



Measurements [Cope] 



Millimeters 



Length of true molar series (2.75 inches) 67 



Length of last molar 25 



Width of last molar 26 



Etymology. — fontinalis, of or from a spring, hence 

 original; in allusion to the primitive characters. 



Present determination. — Cope was in error in inter- 

 preting the teeth of this skull, which belong to a very 

 juvenUe animal, the teeth exposed being the last 

 upper mUk tooth, dp*, the first and second molars, 

 m*, m^. The cranial characters, too, are very juve- 

 nUe. So far as they serve to guide us, the animal 

 probably belongs to the genus Palaeosyops, and also 

 probably to a distinct species, from a low geologic 

 level, possibly Bridger A. 



Figure 98. — Cope's type (holotype) of Palaeosyops diaconus 

 Left upper teeth. Am. Mus. 5106. After Cope, 1885. One-half natural size. 



Thus the last three molars have the same anteroposterior 

 length, while the space occupied by four premolars is shorter. 

 The anterior and posterior cingula of the true molars are very 

 strong, but it is not weU marked on the inner side between the 

 cones. The latter are acutely conic, and the median anterior 

 tubercle is strongly developed. Although the wearing of the 

 teeth indicates maturity, the enamel is coarsely and obtusely 

 rugose. The fourth premolar differs from that of L. major 

 in its smaller size relatively and absolutely and in the presence 

 of a prominent vertical tubercle on the outer face, rising to the 

 angle of the deep notch between the lobes. The third premolar 

 is as wide as the fourth and about as large as the corresponding 

 tooth in L. major, but different from it in the absence of tubercle 

 and ridge that mark its external face. The first premolar has 

 two roots, and the canine is large and short. 



Measurements [Cope] 



Millimeters 



Length of entire molar series 171 



Length of true molars 106 



Length of last molar (crown) 42 



Width of last molar (crown) 43. 7 



In comparison with Marsh's description of his P. laticeps, 

 the measurements are all larger, and the enamel is as rugose as 

 in L. major, instead of smooth. The shortening of the pre- 

 molar series is greater in P. diaconus; thus in P. laticeps the 

 two sets of molars are related as 94 to 61 millimeters; in the 

 present one, as 106:65; were the proportions similar, the length 

 of the premolar series should be 69 millimeters. 



