RODEHTTIA ARVICOLINAE ARVICOLA RIPARIA. 



523 



Measurements. 



Nose to occiput 1.40 



eye .55 



car ~ 1.16 



root of tail 4.40 



end of outstretched hind legs 5.90 



Tail from root to end of vertebrae 1.75 



hairs 2.00 



Prom long hairs of back to end of vertebrae . . j 1.45 



Ears, height, posteriorly 



anteriorly . ... .55 



internally above skull .35 



width 42 



Arm 



length of fore arm .66 



from elbow to end of claws..... 1.15 



forefoot to end of claws . .45 



longest toe and claw.. .27 



longest claw .... .10 



Leg, from knee joint to end of claws 1 .56 



tibia .90 



hind foot from heel to end of claws .80 



longest toe and claw................ .32 



longest claw .11 



Inches. 



In giving an account of the skull, I have selected that belonging to the specimen of Major 

 Leconte, above referred to, as perhaps serving better for the purpose I have in view than that 

 of the animal just described. 



The skull in this specimen (VVy ) is unusually long and narrow; its width, 50 hundredths its 

 length, or barely over half. The molars are about 23 hundredths of the total length ; the mea 

 surement being: Length of skull, 1.18 inch ; width .60 ; length of molars, 28. The occipital 

 foramen is rather broader than high. The cranium projects antero-externally into the inter- 

 zygomatic cavity as a well defined obtuse angle. The interparietal bone is long, and is truncated 

 on the outer sides, sending out a point to the backward prolongation of the temporal bone. 



The upper incisors are broad ; their cutting edges, taken together, about as long as the crown 

 of the anterior tipper molar. The anterior surface broad, convex, although, as usual, there is a 

 very shallow concavity towards the outer edge. The last molar is a little longer than the middle 

 one. It has three vertical groves on each side. There are three salient angles on the outside, 

 besides the C-shaped loop which succeeds those as a long curve, convex externally, and passing 

 round to the inner side of the tooth. Here there are three salient angles ; or four, including 

 the end of the C ; in fact, the two ends of this curved loop constitute two of the four inner 

 salient angles. There are in all five islands of dentine, completely enclosed by loops of enamel ; 

 one anterior, one posterior, one internal, and two external ; all are triangular except the pos 

 terior, which is curved as described. 



