MIMOMYS 359 



Tuccimei regards as a character of advanced wear, which would 

 have appeared a little later on in the somewhat older specimen — 

 but from the ni^ of the latter the " islet " has in reality vanished 

 for ever. Molar teeth resembling those of Arvicola in pattern 

 and size but provided with roots were recorded by Forsyth 

 Major from the lignite of Leffe, in Lombardy, in 1872 (Atti Soc. 

 Ital. Sci. Nat., 15, p. 389) ; whether these should be referred to 

 M. plioccpnictis or to some other species of Mimomys is unknown. 



Lastly from Hungary Mehely has described and figured from 

 the late Pliocene deposits of Beremend, Csaruota, and Berg Nagy- 

 Harsany the most perfect remains of M. plioccenicus yet 

 discovered. 



Characters. — Size medium; tooth-row measuring 7-8 mm. 

 in length. Skull practically unknown. Palate as figured by 

 Mehely (Ann. Mus. Nat. Hungar., 12, Taf. iii, fig. 2) not essentially 

 different from that of Arvicola,^ but probably with an unusually 

 short and broad posterior median sloping septum ; maxillo- 

 palatine suture extending forwards to a point opposite the 

 postero-internal salient angle of ni^ ; anterior palatine foramina 

 terminating posteriorly a little in advance of the tooth-rows. 

 Outer wall of the infraorbital canal ('" masseteric plate ") sub- 

 stantially as in other Microtines. 



Mandible with moderately large angular and coronoid pro- 

 cesses ; the lower incisor crosses from the lingual to the labial 

 side of the jaw beneath the posterior root of Wj, displacing m^ 

 lingually, and ascends the condylar process to a point above 

 the level of the dental foramen ; the termination of the alveolus 

 of the incisor is marked by a strong protuberance upon the 

 outer side of the bone below the condyle ; condylar process 

 somewhat inflected above the just-mentioned protuberance (see 

 Mehely, op. cit., Taf. iii, fig. 5). 



Cheek-teeth with perfectly alternating triangles, and re-entrant 

 folds containing cement. Characterized especially by the early 

 development of the roots, and by the reduction of the third 

 outer fold of ??ij and of the second inner fold of m^. In each 

 case the reduction of the fold takes place by the insulation of 

 its deeper and inner portion, and in adult stages of wear the 

 insulated portion of the fold is represented upon the worn surface 

 of the tooth by a long persistent enamel islet. In this species 

 the formation of the tooth-fangs commences before the reduction 

 of the two molar folds just named becomes apparent at the 

 wearing surfaces of the teeth. 



Upper cheek-teeth. — 7n^ and m^ (Fig. 100, i.->-i8) with three 

 roots each in adult stages of growth; the third root compara- 



' The onlj' palate of this species known to me is that described and 

 figured Ijy Mehely ; he says of it that it is " nach dem Evotomys — Typus 

 pehaut, steht aber zu Dolomiji nahe." The posterior edge, as shown in the 

 figure cited, seems to be slightly mutilated and rather thick; it appears 

 to rae that there is room for a very short, broad, median sloping septum 

 which has been broken awaj'. 



