538 Dr. C. I. Forsyth Major on the 



feeble antero- external cusp besides. The milk-tooth is 

 similar in shape ; only the external cusps and the internal 

 cusp are more strongly developed ; it is also provided with 

 an anterior basal cusp. 



The remains of the external cusps are even yet occasionally 

 found in the case of the C.d. of both genera ; for Ericuhis 

 see Lechers paper * ; they are still better developed on the 

 C.d. of Echinops, which likewise possesses in addition a 

 slight anterior basal cusp. On the C.d. of both genera are 

 also found remains of an interior basal cusp. 



Centetes. — As in the case of Echinops and EricuJus, P. 1 

 swp. differs very little from the milk-tootli and from J/. 1 ; 

 it is true that here also the antero-external cusp is somewhat 

 more independent and is placed higher up, but the difference 

 is perceptible only in teeth which are intact. Apart from 

 this, the tooth is more quadrate in outline, and the triangle 

 formed by the external cusps and the united para- + raeta- 

 cone does not project so far towards the interior as in its 

 precursor in the milk-dentition and in the molars. — P. 2 is 

 the largest and tallest in the molar series ; it possesses a 

 fairly large postero-internal cusp, as well as a minute anterior 

 basal cusp; of the remaining external cusps only a single 

 one, confined to the postero-external angle, is present. Tiie 

 transition in form between this tooth and the small secodont 

 P. 3, in which the anterior basal cusp is wanting or only 

 ^ust indicated, is quite abrupt. It is different in the milk- 

 dentition : P.d. 2 is a tooth of a very elongated shape, with 

 external cusps better developed than in the case of its per- 

 manent tooth ; the foremost of these particularly is more 

 strongly developed than in the latter, and especially than iu 

 the permanent tooth of Ericulus and Echinops. — P.d. 3, 

 although already strongly compressed longitudinally, and 

 without, or only with a slight indication of an anterior basal 

 cusp, still shows in fresh specimens traces of the postero- 

 external cusps ; it exhibits^ further, a remnant of an internal 

 cusp, and, lastly, an accessory cusp behind and below the 

 main cusp (as on P.c7. 2, P.d. 3, P. 2, and P. 3 of Oryzo- 

 ryctes — see below) ; this, however, is wanting on certain 

 specimens, in w hich case the posterior basal cusp is more 

 strongly developed. — Of the milk-incisors the foremost pair 

 alone possesses a distinct posterior basal cusp ; in the case 

 of I.d. 2 and l.d. ?>, which in the fresh condition are uncinate 

 and recurved, this is scarcely indicated. On the other hand, 



* Anat. Auz, xiii. p. 521, tig. 4. 



