1893.] T)E. C. J. rORSYTH MAJOR OX ■NriOCBXE f^QFTRRELi?. 208 



menclature) ' more or less transversely uuited, togetlier with 

 Osborii's paracoiivJ '-, and include between them what I ha^e called 

 the anterior transverse Aalley. Owing to the much-woru con- 

 dition and partly too, perhaps, to the feeble development of this 

 anterior part — as found in some recent Sciari and in Arctom>/s — the 

 anterior valley has vanished in the fossil molars, though I thinlc that 

 some traces of it are still Aasible in the first and third molar of 

 Scott's figures ^ so that, in order to find out the typical triangle, 

 Scott has encroached on a\ hat trituberculism declares to be a late 

 addition to the inferior molars, for he considers, as it Avere, the 

 postero-iuternal cusp, Osborn's eiitoconid, of the " heel" to be the 

 postero-internal part of the typical triangle. "What he calls the 

 talon behind, is but the median cusp (lijipocomdid) of Osborn's 

 talon. This hypoconulid is in fact the real " talon," viz. that part 

 w hich is so generally well de\'eloped on the posterior side of third 

 lower molars, but which in many Sciuromorpha can be distinctly 

 made out in the anterior molars too, as A^ell as in milk-teeth of 

 LepHs and JI)/oh(/vs, and both in milk-teeth and permanent inolars 

 of Lufjudna and Tiianomi/s '. 



The conclusions to be drawn from the foregoing analysis are, 

 1 am glad to state, the very same at Mhich Scott has arrived, as 

 they tend to show, exeu more unmistakably, " that the Eodents are to 

 be derived from the same generalized grou]^ of primitive placental 

 Mammals, the Bunotheria, to which we refer the origin of the 

 Ungulates, Creodonts, and Lemuroids ""'. i ii respect to what Scott 

 considers plainly to b(3 '' the tritubevcular pattern" of superior molars, 

 it cannot be denied that there appear three principal cusps, two 

 external and one internal one, in the iipper molars of Plesiarefonu/s 

 scuiroldes ; but there are other parts to be seen, even in these much- 

 worn molars, and I have already pointed out that it is dangerous 

 to draw inferences from ironi teeth. 



Very similar remarks apply to t\\ o papers by Schlosser ", in \\hich 

 this author endeavours to refer the molars of Rodentia to trituber- 

 culism. I therefore refrain from discussing them at length, and I 

 wish only to remark u])on the second of tlie papers quoted. Scldosser 

 asserts in the most positive manner, wliat at first sight appears to be 

 a startling fact, that Plesladnjns and Proioaddjdii, from the Lower 

 Eocene of Eeims, are Eodentia. Plc.nadajns had previously been 



' (-'f; <". //•. H. F. Osborn and J. L. Wortrnaii, " Fossil Mammals of the 

 Walisatcb aiid Wind River Beds." Collection of IS'.ll. L. r. p. 86, figs. 1 & 2. 



^ L. c. p. 470, and pi. xi. fig. I rK 



' See also the inferior molars o{ " I'li'siailii/iis" in Lemoinc, " Etudo d'en- 

 semble siir les dents des Mammifrros fossiles des environs de Reims '' (Bull. Soc. 

 Geol. de France, trois. sc'i-ie, t. xix. Mni ISill, pi. x. fig, (',;"» c), and of iJniicii- 

 daijis, ibid. ))1. xi. fig. 14(i'', 14()>-.<. 



' Scott , /. v. ]). 47^. 



*■■ Mi»x Schlosser, "Die Differcnzirnng des Siiiigclliiorgobisscs " (Biol. Contra- 

 blatt, Band x. Nos. W & <), Erlangon, 1 & if) June 1890, pp. liM, 2rA).—/,/. '• Ucbcr 

 die systeniatiscbo Sirilmig der (latlinigen J'/i.iiada/iis, Vrntoadapis, I'leiintujj/i/o- 

 thcrium und Orlhaxijiihlheriuiu" (Neues Jidnb. f. .Mincralogie, Geologic iiml 

 Paliifrntologie, Jabrgang 1892, Hand ii. pp. 2'>\). 24lt). 



