62 PROCEEDINGS OF THE ACADEMY OP [1881. 



I am not yet prepared to abandon this opinion, nor to affirm that 

 ants do produce audible sounds by proper stridulating organs ; 

 but simply record the structural possibility of such behavior. 



Since making the above note, Mr. Swinton's work on "Insect 

 Variety " ^ has reached me. The author records an example of 

 what seemed to be an act of stridulation by a small yellow ant, 

 Myrmica ruginodis. 



This insect was observed stationed near the edge of an inverted 

 wine glass, underneath which it had been confined, its head down- 

 ward, rapidly vibrating its abdomen vertically from the pedicle, 

 and simultaneously giving out a continuous singing sound, in 

 color and intensity resembling the sharp whining of the little 

 dipteron Syrilla pipens. 



Concluding that the rhythmical motion accompanying the 

 music indicated this ant as a stridulator, the author undertook a 

 microscopic stud^^ of its anatomy, from which the following facts 

 appear : ^ The ant belongs to the family Myrmicid^, which are 

 distinguished from the Formicid^, to which our honey ant 

 belongs, by having two knots or nodes to the petiole. The second 

 or posterior knot is commonly the larger, and is placed quite near 

 to the anterior pole of the abdomen. Upon the insertion of the 

 abdomen into this node, were observed twelve minute yet regular 

 annular striae. (PI. X, fig. 81.) This stria'ion was produced, but 

 less distinctly, upon the articulation of this (the second) node 

 with the first (anterior) node. It was conjectured that the rapid 

 movement of these joints of the petiole, back and forward upon 

 each other and upon the abdomen (like the jointed tubes of a 

 telescope), produced the sound above described. As the nodes 

 are to be regarded as abbreviated segments of the abdomen, and 

 as the abdominal segments have already been shown to be capable 

 of movement one upon another, Mr. Swinton's interesting obser- 

 vation gives new value to the suggestion above made concerning 

 the structural possibility of stridulation in the honey ant and 

 others of like organism. 



1 "Insect Variety, its Propagation and Distribution," by A. H. Swin- 

 ton, member of the Entomological Society of London, p. 106, and PI. VI, 

 fig. 7. 



2 The writer's account is somewhat confused by false punctuation, and 

 he falls into the error of conjecturing that the small worker may have been 

 a male. I have given my understanding of the structure as derived chiefly 

 from the figure, which I reproduce with some alteration. 



