228 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
Genus SYNAPTOMYS, Baird. 
Synaptomys, Barrp, M. N. A. 1857, 558 (sub Myode), and p. xliv.—Covrs, Proc. Acad. Nat. Sci. Phila. 
1874, 192. 
Dracnosis.—Root of inferior incisor ending abruptly opposite last lower 
molar. Faces of superior incisors longitudinally grooved near outer edges. 
Construction of molars and general cranial characters as in Myodes; palate 
ending as in typical Arvicola. External characters as in Arvicola; ears equal- 
ing or overtopping the fur; tail equal to or longer than hind foot. Pelage 
very soft and full. 
The preceding paragraph gives the essential characters of the most 
remarkable genus of the subfamily—oue singularly combining the peculiari- 
ties of two other widely separated Arvicoline genera. It may be defined in 
a word as the skull and teeth of Myodes in the body of Arvicola, with the 
additional sui generis feature of grooved upper incisors. 
This genus was happily characterized in 1857 by Professor Baird, 
but upon such imperfect and unsatisfactory material* that he did not for- 
mally introduce either the genus or the species in the body of his work, 
though he gives Synaptomys as a subgenus of Myodes and catalogues S. 
cooperi in his introductory list (p. xliv). Doubtless in consequence of these 
circumstances attending its first publication, the remarkable form, although 
defined, as far as the materials went, with precision, has scarcely been recog- 
nized by other naturalists. We are able to confirm the validity of the genus 
and add all the details hitherto deficient. 
Since 1860, the skin of some small Arvicola collected in August, in 
Skaget Valley, by Dr. C B. R. Kennerly, has lain unnoticed in the Museum of 
the Smithsonian on account of its inaccessible condition, having been skinned 
through a small abdominal aperture, the skin left turned wrong side out and 
stretched on a hooped twig, Indian-fashion ; nothing thus appeared from the 
outside, even the tail and hind feet being tucked in out of sight. A crushed 
skull, uncleaned, fortunately hung by the lips. In this condition, the speci- 
men was entered in the Smithsonian archives, some twelve years since, as 
“Arvicola oregona”, a presumptive identification having been ventured upon 
the strength of the locality and apparent small size of the object. During 
*No. $354, Mus. Smiths., merely a rat-eaten bunct of fur, lacking head, tail, and three of the 
feet, but with one cf the fore feet attached, and accompanied by a defective skull; and No, 1368, a skin 
with the feet and tail, but wanting head and skull. Locality unknown, but supposed to be one of the 
Northern United States. Received from Mr. William Cooper. 
