228 



MONOGRAPHS OF NORTH AMERICAN RODENTIA. 



Genus SYNAPTOMYS, Baird. 



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Sj/naplomya, Daikd, M. N. A. 1857, 558 (xub Atyode), aud p. xliv.— Coueh, Troc. Acoil. Nat. Sci. Philn. 

 1874, 192. 



Diagnosis. — 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 Myodpo; palate 

 ending as in typical Arvicola. External characters as in Arvicola; ears equal- 

 ing or overtopping the fur; tail equal t^ 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^-one 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 tiie 

 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 8. 

 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 

 SUaget Valley, by Dr. C B. R. Kennerly, has Iain 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. Duiing 



* ^0' mi' Mu8. Smiths., merely » rnt-eaten bunch of fnr, lockin); head, tail, and three of the 

 feet, but <vitli one cf the fore feet attached, and accompanied by a defective alcuU ; and No, 1368, a skin 

 with the feet and tail, but wanting head and ukull. Locality unkuowii, but gapposed to bo one of the 

 Northern United States. Received from Hr. William Cooper. 



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