Geological magazine . s also entailed the division ofthe median and posterior valleys of the Ancliitherium molar into aninner and an outer moiety. The remaining type of Perissodactyle molar we have to noticeis that of the Ehinoceroses (Fig. 5). Here Prof. Osborn has intro- FiG. 4.—Right uppermolar of Equus sienonis;letters as in Fiff. .3. 320 Reviews—Prof. S. F. Qsborn—Molars of Perissodactyla. duced three convenient new descriptive terms, which will be equallyapplicable to the molars of other Perissiodactyles. It appears thatthe outer wall of the Ehinoceros molar is formed by the union ofthe
Geological magazine . s also entailed the division ofthe median and posterior valleys of the Ancliitherium molar into aninner and an outer moiety. The remaining type of Perissodactyle molar we have to noticeis that of the Ehinoceroses (Fig. 5). Here Prof. Osborn has intro- FiG. 4.—Right uppermolar of Equus sienonis;letters as in Fiff. .3. 320 Reviews—Prof. S. F. Qsborn—Molars of Perissodactyla. duced three convenient new descriptive terms, which will be equallyapplicable to the molars of other Perissiodactyles. It appears thatthe outer wall of the Ehinoceros molar is formed by the union ofthe primitive paracone {pa.) with the metacone (me.), to which isadded the anterior ridge (a.) ; and for this outer wall the termectoloph is suggested. The anterior transverse crest, formed by theunion of the paracone (pa.), protoconule (pi.), and protocone (pr.)is termed the protoloph; while for the posterior transverse crest,compounded of the metacone (me.), metaconule, and hypocone (hy.)we have the name Fig. 5.—Left upper molar of Ehinoceros palceindicus. Letters as in Fig. to me. is the ectoloph; a. to pr. the protoloph; and me. to h^. themetaloph. The process projecting from the metaloph into the medianTalley is the crotchet. In the primitive Ehinoceros molar the three elements—anteriorridge, paracone, and metacone—of the ectoloph are represented bydistinct vertical ridges; but some or all of these tend to disappearwith the increasing flatness of the outer surface of this part of thetooth as specialization increases. And it is somewhat noteworthythat while in the most specialized types of teeth, like those of theIndian Rhinoceros, of the two African species, and of the extinctWoolly Ehinoceros, the development of the paracone is less markedthan in the more generalized Sumatran and Javan species; yet theridge marking the metacone is decidedly more pronounced. Althoughthere is no distinct representative in the Ehinoceros molar of the Reviews—Geologi
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectgeology, bookyear1864
