542 Dr. C. I. Forsyth Major on the 



0. hova tliis tooth is even somewhat more strongly developed 

 than in that of the other two species. (The G. of Microgale 

 is generally much feebler — fairly stout only in M. pusilla.) 

 The tip of the G. of Oryzoryctes is recurved, more so in the 

 lower than in the upper one. All the canines have a poste- 

 rior basal cusp, which is more strongly developed in those of 

 the upper jaw. — The upper /. 1 converge towards each other 

 and are provided with a strongly developed posterior basal 

 cusp ; /. 2 has, as in the case of Microgale [cf. Leche, loc. 

 cit.)j an anterior and a posterior basal cusp, of which the 

 former is still present even in the feebly developed /. 2 of 

 M. qracilis. 1. 3 is rudimentary, with indications of anterior 

 and posterior basal cusps. Of the lower /. the middle one is 

 the strongest, the hindmost the weakest and similar in form 

 to /. 3 sup. 1. 1 and /. 2 are provided with a posterior basal 

 cusp [I.d. 2 appears to possess two) . 



Thus we see — to recapitulate the morphological relations 

 of the jn-emolars, at least for the extremes of our series — that 

 P. 1, P. 2, and P. 3 in the upper jaw {M. 1, P. 1, and P. 2 in 

 the lower) of EcMnops correspond to M. 2, ^^. 1, and P. 1 of 

 Oryzoryctes hova in general form, and therefore without 

 doubt in function also. Analogues of the two secodont teeth 

 — P. 2 and P. 3 sup. — of 0. hova are entirely wanting in 

 EcMnops. As has been mentioned above, the G.d. of Echi- 

 nops and Ericulus are still more premolariform than those of 

 all other Centetidas which have here been discussed, while 

 their /., in the permanent set at least, are not more compli- 

 cated than those of Microrjale and Oryzoryctes — rather tiie 

 contrary. Up to a certain point, therefore, in the case of 

 Echinops and Ericulus, G. and the posterior /. assume the 

 functions exercised by the anterior premolars in the case of 

 other genera. 



This condition partly coincides with that to which Leche 

 has drawn attention and termed " release {Entlastung) and 

 reduction of the middle antemolars with simultaneous higher 

 development of the anterior incisors " *, which we now have 

 briefly to discuss. 



According to Leche's detailed account of this process f, 

 the part played therein by the lower /. 1 and G. is especially 

 characteristic. " The former," he writes, " is reduced to the 

 same extent as /. 2 is developed, and it finally disappears 

 altogethei", so that in the lower jaw it is /. 2 that attains to 

 the degree of development corresponding to that of the upper 



* Anat. Anzeiger, xiii. 1897, pp. 521, 622. 



t " Zur Entwicklungsgescliiclite des Zahnsystems der Saugethiere &c. : 

 I. Ontogenie," Bibl. Zool. Heft 17, 1895, p. 'i'd. 



