30 Hoiccll — Mammalfi of the Middle Mississippi Valley. 



(lens ))uilt umler the roots of large tupelos'or cypresses growing in deep 

 water, were examined, but only one young muskrat was caught. During 

 the winter the rats l)uild numerous large houses in the lakes or marshes, 

 hut by spring these dens are usually all destroyed or carried away l)y high 

 water. 



Five specimens, taken in Horseshoe Lake, Illinois, in December, agree 

 very closely with September specimens oi zlbethicns from ^Massachusetts. 



Muskrats were reported to occur at the following localities: 



Missouri : Horseshoe Lake, St. Charles County; St. Francis River; Cush- 

 ion Lake; Marble Hill. 



Illinois: Olive Brancli; Wolf Lake; AVoodlawn; Olney; Kansas; Shaw- 

 neetown. 



Kentucky: ^Midway; Mammoth Cave; Jackson. 



Synaptomys gossi Merriam. 



(iOSS LEMMING MOUSE. 



Tills sju'cies, previously known only from Kansas, was found in nund)ers 

 at Horseshoe I^ake, St. Charles County, Missouri, April 21 and 22, and a 

 goo<i series of specimens was secured. A large colony had occupied a low 

 marshy meadow close to the Mississippi River. At the time of my visit 

 tiie water in the river was very high, and the meadow was overflowed to 

 a deptli of 12 to IS inches. The mice had been driven from their burrows 

 l)y the high water, and were hiding as well as they could on tussocks and 

 under jiatches of floating debris. "When disturbed they ran rather slowly 

 over the submerged vegetation and swam freely, but were easily over- 

 taken. INLuiy had been killed by dogs or other predatory animals, and I 

 was able to get as many specimens as I needed by catching them in my 

 hands. The burrows in this meadow were on the little hillocks, the 

 entrances near the top. Thus they are probably dry except in times of 

 very high water. The entrances are perfectly open and not concealed 

 under vegetation as is the hal)it of S'/naptomi/s cooper i in the eastern 

 States. Well-beaten runways extended out from tlie burrows and under 

 the dead vegetation. A single specimen taken June 5 in an old dry 

 meadow at Odin, Illinois, is provisionally referred to this form. It agrees 

 with (jossi in color, but its skull is too young to l^e positively identified. 



At the time this species was described, only a few specimens were in 

 existence and no skins were available. Since then the skins collected at 

 the tyiie locality by (loss have come to light and the Biological Survey has 

 received .si.x specimens from Fort Leavenworth, Kansas, collected by Dr. 

 B. H. Dutcher. In view of the scarcity of this species and the lack of any 

 description of its external characters, the following brief synop.sis has been 

 prepared : 



Specific characters.— Size large and stocky — the largest of the genus; 

 skull massive, larger than that of JirJaletcs (much larger tlian coopcri) but 

 with rostrum both actually and relatively narrower; colors dark. 



Color. — Adults in full pelage (Kansas, April and June): rich reddish 

 brown above, with an admixture of black hairs; sides paler; underparts 



