46 FIELD COLUMBIAN MUSEUM ZOOLOGY, VOL. III. 



or three nests for use at one time or continually shifts about, build- 

 ing a nest in which to live while it constructs another, for fully 

 two-thirds of the nests were always uninhabited. Their nests are 

 firmly and neatly woven of grass and fine weed stalks, anchored 

 to the surrounding tufts of grass and floating in the water. But 

 two exceptions to this were noted and then the nests were built 

 against the base of a bush and a stump respectively, with only 

 about a foot of water beneath. These two nests had but a single 

 entrance, which was at one side and of course under the water. 

 All the other nests I saw were placed in water ranging from 18 

 inches to 3 feet in depth, and invariably had two entrances, one 

 on each side, well under the water. The nests are a perfect 

 dome shape as they float on the water, and average 14 inches in 

 diameter by 12 inches high. That is the nest which appears 

 above the surface of the water, but it is generally resting on a 

 mass of half-rotten grass ranging from 18 inches to 24 inches in 

 diameter, and a few inches thick. The platform on which the 

 rat both sits and sleeps is only about 4 inches wide, the entrances 

 being on either side of it, and often this platform is quite wet, in 

 fact it is so near the water it could not well be otherwise: I 

 once saw some short pieces of marsh grass on the little platform 

 and being perfectly green must have been serving as a meal for 

 the rat. Luck seemed against my securing a really good photo 

 of their nests, but the one I did secure finally will give a good 

 idea of what they appear like. None of the nests were placed 

 over 20 feet from shore and were invariably built among the high 

 marsh grass, which so closely resembles the broom sedge grass 

 of the dry old fields. I never saw the animals swimming about 

 in the water,. in fact I saw but one alive and free, and that one 

 was sitting on top of its nest one day during a hard rain, disap- 

 pearing into the water like a flash when it saw me. I believe one 

 rat is all that frequents a nest. On opening a nest on February 

 22d I was delighted to find it contained two young ones $ and 

 9 their eyes yet unopened and I should judge about a week 

 old. They had a thick coat of very dark hair and were very 

 pretty, but odd looking little fellows, their noses being very 

 blunt, and resembling nothing so much as the pictures of 

 young hippopotami I have seen. These two young ones were in 

 the nest referred to above as being built against a stump. This 

 nest was far more substantially built than any of the others, and 

 the interior was very dry and nice. These little fellows must 

 have been born about the i5th of February, from which we must 



