FOSSIL AND EECEXT LAGOMORPHA. 4i9 



termination like the teeth anterior to them (figs. 1, 13, 19). The outer view {b) shows the 

 whole of the outer side devoid of enamel. 



The levelling effect of trituration tends to produce a more lophodont character of 

 the crown. In an unworn condition, however, these teeth present a much more 

 bunodont appearance, and it requires a very small effort of imagination to trace them 

 hack — conspicuously so the intermediate in the series, which are more typical — to a more 

 hrachyodont as well as bunodont form, in which the predominant feature is that the 

 cusps, while the intervening enamel folds would appear as shallow valleys, are not yet 

 filled with cement. We meet with such hrachyodont types in the Eocene (classed as 

 Creodonts and Lemuroids) ; more than any other, the Eocene " Felycodus helveticus 

 E-iit.," and Plesiadapis, both so-called Lemuroids, show teeth in close agreement with 

 Titanomys. Let, vice versa, a hrachyodont molar of the shape of " Pelycodus, 

 helveticus " (PI. 36. fig. 3) or Plesiadcqris (PI. 36. fig. 2) l^ecome somewhat more 

 hypselodont by the heightening of its shaft, and let the valleys between the cusps be 

 filled with cement, and the result will he a Tifaiiomys-tooth. This I had in view when, 

 on a former occasion *, I stated that the structure of the lagomorphine molar can 

 be traced back to a " pelycodoid type." 



2. Geniis Prolagus. 



Lagomys, G. Cuvier, Oss. foss. iv. pp. 21, 22 (1812), sec. ed. iv. pp. 200, 203 (1823) ; Rud. Warier, 



Kastner's Arch. f. d. gcs. Naturlehre, xv. pp. 1-i, 18 (1828) ; id. Oken's Isis, p. 1136 (1829) ; p. p. 



H. V. Meyer, Neues Jalirb. 1836, p. 58 ; p. p. id. Foss. Saugetli. etc. von (Eningen, p. 6 (18i5) ; 



Waterliouse, Nat. Hist. Mammalia, ii. p. 32 (1848) ; Lartet, Not. Colline de Sansan, p. 21 (1851) ; 



p. p. Fraas, Wiirtt. naturw. Jaliresl). xxvi. p. 171 (1870); Lydekker, Cat. Foss. Mamm. Brit. Mus. 



i. pp. 256, 257 (1885), v. p. 325 (1887). 

 Anoema, Konig, Icones Foss. Sectiles, pi. x. fig. 126 (1825). 

 Prolagtis, Pomel, Cat. mctli. p. 43 (1853). 



Mtjolayus, Hcnsel, Zeitschr. deutsch. geol. Ges. viii. p. 695 (1856). 

 Arch(eomys, Fraas, Wiirtt. naturw. Jaliresli. xviii. p. 130 (1862). 



G. Cuvier was first to recognize that some fossil remains, which belong to the above 

 genus, are those of a lagomorphine Piodent ; he figured and descrilied them from an 

 ossiferous breccia of Corsica, and later from a breccia of Sardinia, considering them 

 to be a species oi Lagomys. 



In 1825 Konig figured, in his ' Icones Foss. Sectiles,' a skeleton from CEningen. 



H. V. Meyer (1836) notes among the Mammals of CEningen the genus Lagovii/s; the 

 same, according to Murchison, had been previously suggesied by Laurillard t- H. v. 

 Meyer further supposes that Konig's Anoema might belong as well to the former genus. 



From the Miocene of Sansan (Gers) and Venerque (Haute-Garonne), Lartet mentions 

 a lagomorphine Eodent of the size of a large rat, which he proposes to unite with 



* P. Z. 8. 1893, p. 208. 



t R. I. Murchison, " On a Fossil Fox found at (Eningen, near Constance,"" Trans Ueol. Soe. London, iii. 2, 

 p. 285 (1832). 



SECOND SERIES. — ZOOLOGY, VOL. VII. 63 



