320 MAMMALIA: GLIRES. — XLVIII. 
short, ears small). A large sub-family, Northern Hemisphere, many 
species, including the lemmings, polar. (AMicrotine.) 
6, Tail flattened, scant-haired; hind feet partly webbed. . . . Fiper, 542. 
6b. Tail subterete. 
c. Upperincisorsgrooved. . . . . - . . + . SY¥YNAPTOMYS, 543. 
cc. Upper incisors not grooved. 
d. Molars rootless from persistent pulps. . . . . Mucrorus, 544, 
dd. Molars rooted, small and wenk (back red). . . Evotomys, 545, 
ddd. Molars rooted, large and strong (back not red) PHENAComys, 546, 
aa. Incisors narrow, compressed; molars rooted, tuberculate, with crenate mar- 
gin (body slender; eyes and ears large; snout pointed; motions rapid). 
e. Molars of upper jaw with tubercles in ¢wo series (American species), 
J. Mouse-like. (Cricetine.) 
g- Upper incisors grooved. . . . REITHRODONTOMYS, 547. 
gg. Upper incisors not grooved. 
h. Tail scant-haired, very long, as long as head and body; ears 
verysmall. . . . . A . » Oryzomys, 548. 
hh, Tail closely haired, much lougar than head; ears large. 
Perowyscus, 549. 
hhh. Tail closely haired, scarcely longer than bead. 
Onycuomys, 550. 
Jf. Ratlike, molars with re-entrant angles; length, with tail, a foot 
or more. (Neotomine.) oR * ee Neoroma, 551. 
ee. (Molars of upper jaw, with tubercles in three series; soles aakeds 
tail long, scant-haired orscaly (Murine ; old world species, introduced 
in the United States). . . 2. - 2. «+ © «© » «© +» « « + Mus, 
542, FIBER Cuvier. (Lat., beaver.) 
1039. F. zibethicus (L.). Musxrar. Color dark brown. 
L. 223. T.11. E,N.Am.; everywhere. Largest of our Muride ; 
building houses or burrows about streams and ponds, (Lat., 
zibetha, the Civet, from the odor.) 
1040. F. macrodon Merriam. Color very much darker; 
teeth very much larger, others like the common muskrat. Dismal 
Swamp, Va. (akpés, large; d8ous, tooth.) 
543. SYNAPTOMYS Baird. (cvvdrre, to join; pis, mouse; 
connecting lemmings and mice.) 
‘1040. S. cooperi (Baird). Lemmine Mouser. Mouse-color, 
grayish below; head very large with long whiskers; fur soft and 
long. L.48. T.%. Minn. to Mass.,S. to mts. of N. C., aremark- 
able animal, between the field-mice and the lemmings (Lemmus). 
(To William Cooper of Hoboken, N. J.) 
1041. S. fatuus Bangs. Similar to S. cooperi, but with much 
narrower upper incisors; the skull smaller. Quebec, N. B., Me., 
and N. H. (Lat., foolish.) 
1042, S&S. helaletes Merriam. Size of S. cooperi, larger fore 
