TJie Lcmwilngfi of the Genus Syjtaptomijs. 



59 



Color. — Upper piirts t^rizzlwl yellowish brown, abundantly mixed with 

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

 with hwff on the belly; tail nearly eoneolor, only slightly paler below 

 than above. 



Cranial and dental cJiaradrrs. — Skull similar to that of *S'. cooperi, but 

 smaller and weaker ; rostrum narrower ; basisphenoid broader posteriorly. 

 Upper incisors very nuicli 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 vertebrpe, 19; hind foot, 18. 



Synaptomys helaletes sp. nov. 



Type from Dismal Swamp, Virginia, No. 75172, $ 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 mandi))le, and larger and more 

 massive skull and teeth. 



C'o/o/-.— Upper parts grizzled gray and yellowish brown, abundantly 

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

 white; tail bicolor, brown- 

 ish above, whitish below; 

 toes usually partly white. 



Cranial and dental cliur- 

 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 vertebrte, 22; 

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

 118.5; tail vertebra?, 21; hind foot, 20.2. 



General remarks. — Synaptomys helaletes, while of essentialh- 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 ui)per 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 mav exist. 



Fig. s.-i^i^uU o{ .Synaptomys ke/a/eies $ 

 (type) X 1^. 



