94 



GIDLEY 



protocone is quite prominent and still typical in form, while in 

 Solenodon it is much reduced and is beginning to divide trans- 

 versely, or more probably is beginning to separate from a like- 

 wise reducing hypocone. This is in favor of the view held 

 by Mivart that the simple inner cusp in Potamogale and like 

 forms is in reality the fused protocone and hypocone. The 

 reduction is carried still further in Centetes, in which two 

 inner cingulum-like cusps appear, one on each side of the 

 enlarged paracone. In Chrysocloris and Hemicentetes the 

 inner cusp (protocone and hypocone) has entirely disappeared. 

 Regarding Mivart's " fusion theory," I am inclined to believe 

 that Woodward has not given due weight to the evidence cited 

 by Mivart and that there is considerable support for this theory 

 to be found in the modern bats and insectivores. Mivart con- 

 sidered the Potamogale molar as an intermediate form between 

 molars of the Talfa type, having tw r o external triangular prisms, 

 and those of Centetes and Ericulus, having only one such 

 prism. He pointed out that in Potamogale there is " a very 

 interesting approximation of the triangular prisms," in which 

 the paracone and metacone, although still remaining distinct, 

 are in very close juxtaposition. This view is strongly supported 

 by a series of bat molars to which Mr. G. S. Miller has kindly 

 called my attention. In this series, which includes Vesfie?-tilio, 

 Scotophilia and Harpiocefhahis^ are suggested the successive 

 steps from Talfa to Potamogale in the insectivore group. 

 Vesfertilio represents the normal or more generalized form, 

 in which the protocone is large, the paracone and metacone 

 are widely separated, and the external styles are nearly equal 

 in size. The mesostyle is much reduced in Scoto-philus and is 

 drawn inward, the paracone and metacone are more closely 

 appressed and the protocone is somewhat shortened. In Har- 

 piocephalus l the mesostyle has disappeared, the parastyle and 



1 The skull of Harpiocephalns from which this description was taken was 

 obtained by Mr. G. S. Miller through the kindness of Oldfield Thomas, of the 

 British Museum. 



Unforunately it came too late to be photographed and figured uniformly 

 with the series. Its place is taken on Plate III, by an outline drawing from a 

 figure for Wilhelm Peters' Fledermause des Berlines Museums fiir Naturkunde 

 (a projected monograph of the bats). 



