540 L)i'. C. I. Forsyth Major on the 



of M. pusiUa, which in other respects has undergone less 

 compression, this has disappeared. 



In the case of Oryzoryctes tetradactyJus and 0. niger the 

 compression of P. 1 has proceeded still further, as is shown 

 inter alia by the considerable reduction of the median ex- 

 ternal cusps ; as in Microgahj three of these cusps are present 

 on P. 1 of Oryzoryctes, but the middle one is not so pre- 

 dominantly developed as in the case of the former genus ; 

 the first is somewhat larger, the second smaller than in 

 Microgale. The '' protocone " still has the same extent as 

 on M. 1 and is bicuspid. Owing to its more compressed 

 form P. 1 agrees much more closely with P. 2 of Microgale 

 than with P. 1 in the latter genus. P. 2 has undergone even 

 more compression : the median external cusps are distin- 

 guishable merely as vestiges on teeth which are intact; 

 the " protocone " is reduced to a minimum. The perfectly 

 secodont P. 3 is of considerable height; it projects above 

 P. 2. Both P. 2 and P. 3, as well as their precursors, show- 

 on the blade, behind the main cusp and halfway up between 

 this and the alveolar margin, an accessory cusp, the inter- 

 pretation of which as the homologue of the metacone of the 

 molars has already been discussed. — In Oryzoryctes hova 

 even M. 1 already exhibits the general outlines of a carnassial 

 tooth. In P. 1 the compression in the longitudinal direction 

 has made to a certain extent still further progress than in 

 the case of the other species ; the " protocone " is likewise 

 bicuspid. P. 2 is altogether secodont, without a trace of 

 median external cusps or " protocone." 



2. Lower Jaiv. — In Ecliinops and Ericulus P. 1 and P. 2, 

 as well as their precursors in the milk-dentition, resemble 

 molars j accordingly even P. 2 is provided with a stout in- 

 ternal cusp, Osborn's melaconid, of which a trace is still 

 present even on P. 3 of Echinojjs. In the case of Ericulus 

 P.d.3, P. 3, C.d., and C. have an internal basal margin, 

 which is still present on the incisors also ; it is much less 

 pronounced in Ecln'nops. P. 3 of Echinops has sometimes 

 only one root. The canine, which is always single-rooted, 

 exhibits now and then a slight median groove down the 

 root. 



Centetes. — Both P. 1 and P.d. 1 are molariform, but P. 1 is 

 larger than the molars. P. 2 is a i)owerlul tooth, almost 

 resembling a canine ; like the corresponding tooth in the 

 upper jaw, it is higher than the posterior molars. An indica- 

 tion of an anterior basal cusp is found only in certain cases ; 

 a posterior basal cusp is present in the form of a talon, which 



