The Lemmings of the Genus Synaptomys. 



59 



Color. Upper parts grizzled yellowish brown, abundantly mixed with 

 black-tipped hairs ; under parts varying from slate gray to whitish, washed 

 with buff on the belly ; tail nearly concolor, only slightly paler below 

 than above. 



Cranial and dental characters. Skull similar to that of S. cooperi, but 

 smaller and weaker ; rostrum narrower ; basisphenoid broader posteriorly. 

 Upper incisors very much narrower than in cooperi. 



Measurements. Average of 2 adults from type locality (measured in flesh 

 by O. Bangs): total length, 124; tail vertebrae, 18; hind foot, 18.7. 

 Measurements of an alcoholic specimen ( 9 ) from Godbout, Quebec : 

 total length, 106; tail vertebrae, 19; hind foot, 18. 



Synaptomys helaletes sp. nov. 



Type from Dismal Swamp, Virginia, No. 75172, 9 adult, U. S. National 

 Museum, Department of Agriculture collection. Collected October 14, 

 1895, by Dr. A. K. Fisher. Original number 1818. 



General characters. Similar to S. cooperi, but with larger head and feet, 

 longer tail, much broader rostrum and mandible, and larger and more 

 massive skull and teeth. 



Color. Upper parts grizzled gray and yellowish brown, abundantly 

 mixed with black-tipped hairs; under parts plumbeous, washed with 

 white; tail bicolor, brown 

 ish above, whitish below; 

 toes usually partly white. 



Cranial and dental char 

 acters. Contrasted with 

 S. cooperi, the skull and 

 teeth are larger, heavier, 

 and more massive ; the 

 zygomata less strongly 

 bowed outward ; the na 

 sals broader posteriorly, 

 and the brain case longer. 

 The rostrum, upper in 

 cisors, and under jaw are 

 remarkable for breadth 

 and massiveness. 



Measurements. Type specimen: total length, 125; tail vertebra, 22; 

 hind foot, 20. Average of four adults from type locality : total length, 

 118.5; tail vertebrae, 21 ; hind foot, 20.2. 



General remarks. Synaptomys helaletes, while of essentially the same size 

 as S. cooperi, has very much larger fore and hind feet and a longer tail. 

 The difference in the breadth and massiveness of the rostrum, mandible, 

 and upper incisors is so great that skulls of the two require no compari 

 son. Still, specimens recently collected by Vernon Bailey in a sphagnum 

 swamp near Washington, D. C., are somewhat intermediate and indicate 

 that intergradation may exist. 



FIG. 3. Skull of Synaptomys helaletes <j? 

 (type) X 1%. 



