64 CHARLES A. COBURN 



The writer desires to add, to the observations already re- 

 ported, an additional record of "singing" mice. About the 

 first of December, 1911, while working one evening in his study, 

 he heard a series of sounds which seemed to come from above 

 the ceiling. At the time, they were thought to resemble the 

 soft chirping of a bird. 



Shortly afterward, some wild mice were needed for breeding 

 experiments and, by means of a trap, two mice, a male and a 

 female, were captured in the room. 



These animals, while being taken to the Harvard Psychologi- 

 cal Laboratory, produced sounds like those previously heard 

 in the room and they continued to do so at intervals after 

 being placed in a laboratory cage. A few days after their 

 capture, the male escaped. Inasmuch as the writer had not 

 separated the two mice, placed each in a separate cage in a 

 different part of the room, it is not possible to state whether 

 the sounds were produced by both the mice or only by the 

 female which remained and continued to "sing." 



The female was mated with a tame mouse and produced, 

 during the period of observation, five litters, thirty-three indi- 

 viduals. None of these offspring produced unusual sounds, 

 nor did "singing" appear in the second or the third generations 

 obtained from these hybrids. 



The "singing" individual, so far as could be ascertained, 

 was a common house mouse (Mus musculus). She was some- 

 what larger than the ordinary wild female, but no other exter- 

 nal peculiarities were noted. She was extremely active and 

 savage and her mate always bore the marks of her teeth. An 

 attempt to mate her with a second tame male resulted in the 

 death of the latter. 



No definite time for "singing" was noted, except three or 

 four days before and for six or seven days after the birth of a 

 litter. It was observed, also, that the individual "sang" 

 sometimes when frightened. 



The sound is best described as a rapid whole-toned trill 

 involving the tones C and D as is indicated below. 



1^ T ^ l J ' ^ --^U^^ 



