110 



Chronicles of Science. 



[Jan., 



Figs. 3 — 5. Illustrating the affinities of Hypsiprymnopsis Rh^ticus.* 

 Fig. 3. 



Fig. 4. 



Fig. 5. 



Fig. 3. Premolar of Hypsiprymnopsis Rhccticus, magnified four diameters. 



Fig. 4. Unworn left lower premolar of Hypsiyrymnus minor, magnified two diameters. 



Fig. 5. Worn right lower premolar of H. minor, magnified four diameters. 



fossil, there is scarcely a trace of plications, so that this character 

 cannot well be used, Mr. Dawkins says, as an argument against the 

 Hypsiprymnoid character of the fossil tooth. 



Mr. Dawkins considers, therefore, the nearest living representative 

 of the fossil to be Hypsiprymnus minor, " or some other of the 

 kangaroo-rats with four plicated premolars ; " but the fossil tooth is 

 not more than half the size of the corresponding teeth in the recent 

 speeies. The relation of Hypsiprymwipsis to Microlestes cannot be 

 determined, because the tubercular true molars are all the remains 

 that are known of the latter genus. 



Hypsiprymnopsis Rlmticus was found by Mr. Dawkins on the sea- 

 shore to the west of \Vatchet, in the hard arenaceous marlstones 

 which yielded the first traces of life in the passage upwards from the 

 red marls of the Trias. Its exact position was 10 feet 6 inches below 

 the bone-bed, and therefore it is very probably, if not certainly, the 

 oldest known trace of the Mammalia, for the Ehaetic Mammalian 

 remains hitherto found, namely, the Microlestian teeth of Frome and 

 Diegerloch, were obtained from the bone-bed itself. The only 

 doubtful question is, Does the bone-bed of Diegerloch represent exactly 

 the same epoch as that of Frome and Watchet ? — the English and 

 German localities being far apart. Besides the distance of the 

 localities, however, there is very little reason why the two bone-beds 

 should not be contemporaneous, but there is equally little proof that 

 they are. 



* Fig. 3 was drawn from the original specimen, kindly lent for the purpose by 

 Mr. Boyd Dawkins ; Figs. 4 and 5 were copied from Figs. 4<z and 46, of Mr. Daw- 

 kin's paper in the ' Quarterly Journal ' of the Geological Society, No. 80, p. 411. 



