COLE ON HABITS OF A MLTSKllAT. 199 



that each but the first bears a pinnule, a very uncommon arrangement 

 at the present time, and the fact that the ovary seems to be confined to 

 the arm, traces of it still appearing in the disk. Ihe probable 

 arrangement in the Blastoids and Cystids, would lead one to suppose the 

 process of evolution had not gone on as rapidly in rotundus as in other 

 forms and that it is more closely related to the geologic crinoids than 

 most of the forms in existence at the present time. 

 Olivet College. June, 1902. 



HABITS OF A MUSKRAT IN CAPTIVITY. 



BY LEON J. COLE AND H. C. TOOKER. 



In spite of the almost complete settlement of the country and the 

 commercial value placed upon its skin the muskrat, Fiher zihethicus (L.), 

 is still a not uncommon resident in the vicinity of Ann Arbor, and its 

 houses may be seen in some numbers in the mill ponds along the Huron 

 river. The following observations upon one of these animals in captivity 

 are not intended as a complete chapter in the natural history of the 

 species, having been made as they were under artificial conditions, but 

 they seem justified by the fact that whatever things an animal does under 

 any conditions are a part of its general activities. For this reason such a 

 study is perhaps as essential for the complete understanding of its actions 

 as are its habits under natural conditions. Some help may also be given in 

 this way to an interpretation of the natural habits, it being necessary 

 however to keep constantly in m,ind as a check to too hasty generalization 

 the changed conditions under which the subject is placed. 



On the morning of November 17, 1901, a full-sized male muskrat was 

 found in a steel trap which had been set the day before in the water at 

 the junction of two runways which ran back through the grass of the 

 river bank. The trap had sprung securely upon the toes of one of the 

 hind feet; otherwise the animal was uninjured. Another trap was sprung 

 gently upon his tail, the first one removed from the foot and also sprung 

 upon the tail ; and so he was carried to the laboratory, where he was 

 placed in a wire cage, which needs a brief description. It was made of 

 galvanized iron wire with meshes about 13 mm. square; outside measure- 

 ments of cage, length 93 cm., height 31 cm., depth 31 cm. A horizontal 

 and two vertical ])artitions divided the interior into six compartments 

 all of which were in communication by doorways, but capable of being 

 shut off from one another by sli<ling doors. Only the three lower com- 

 partments were given over to the muskrat, the upper portion of the cage 

 being occupied by squirrels. Each of the compartments was partially 

 divided by a half-floor of finer wire screen extending forward from the 

 back of the cage. Below the cage was placed a galvanized water tank of 

 about the same length and breadth as the cage and 35 cm. deep. A round 

 hole in the fioor of one of the compartments and an inclined runway led 

 down into the water, while a glass front in the tank gave opportunity 

 for observing the muskrat when he was swimming in the tank. 



When discovered in the trap the muskrat had shown considerable fight, 



