MYOMORPHA. 851 



somewhat nan-owed at their extremities. The tubercles of the first and last 

 difier slightly from those of the superior series. The anterior odd one of 

 the first is smaller; while the posterior outer crescent of the third is well 

 developed, with all the transverse crests. The posterior inner cone is, how- 

 ever, wanting. The details of the inferior molars repeat those of the supe- 

 rior series, but in reversed relation, the external portions of the one being 

 the internal of the other, and vice versa. The inferior incisors are nearly 

 as much curved as the superior ones; they are robust and subtriangular in 

 section. The enamel is smooth, and has a convex surface presented more 

 obliquely outwards than the superior incisors. 



Measurements. 



M. 



Depth of skull at middle of orbit, without molar teeth 0.0060 



Width between orbits 0050 



Length from middle of orbits 0150 



Length from front of zygoma 0100 



Length of superior diastema .... .0075 



Length of nasal bones 0120 



Length of superior molar series 0060 



Length of first superior molar 0025 



Length of third superior molar 0015 



Width of first superior molar 0020 



Width of third superior molar 0016 



Width of nasal bones at middle 0020 



Width of nasal bones distally 0030 



W^idtli between bases of zygomata 0070 



Width of superior incisor tooth 0015 



Length of mandible of another individual to dental foramen 0160 



Length to end of dental series 0115 



Length to front of dental series 0055 



Length from base of vortical symphysis to front of pterygoid fossa 0095 



Depth at diastema 0050 



Depth at middle molar 0055 



Length to base of coronoid : 0090 



Thickness of ramus on front border of masseteric fossa 0040 



Anteroposterior diameter of inferior incisor tooth 0020 



Anteroposterior diameter of last molar 0020 



Width of last molar 0018 



The hundred and more individuals represented by my specimens, evi- 

 dently differed in various minor respects, as in size and robustness. Some, 

 perhaps males, have the muzzle stouter in proportion to the length than 

 others; some are more decurved than others. 



With molar teeth as large as those of the Norway rat the muzzle of 

 the Eumys elegans is not more than two-thirds as long; so that the species 

 was in general proportions smaller and more robust. 



