^ ANTS. 



the .same mother. Several of the different types of venation which have 

 been recognized are represented in the accompanying illustrations (Fig. 

 ii), to which the reader is referred for the names and disposition of 

 llie various veins and cells. 



The Abdomen. This region in ants is very highly specialized in all 

 three sexual phases. In some of the most primitive tribes, like the 

 Amblyoponii and Cerapachysii, there is no sharp separation of the seg- 

 ments into a pedicel and gaster; the basal, though somewhat nar- 

 rower and more accentuated, preserving essentially the same structure 

 as the more distal segments. In most ants, however, there is a well- 

 defined pedicel which ma}' consist of either one or two segments, very 

 movably articulated with each other and with the thorax and gaster. 

 In the subfamilies Dolichoderinae and Camponotinae the pedicel always 

 consists of but a single segment, the petiole, which is morphologically 

 the second abdominal segment. The same condition prevails in most 

 PoneriiKi', except that there is a constriction behind the following or 

 third segment, foreshadowing the development of a postpetiole. This 

 segment is clearly separated off in all Myrmicinse, so that in the ants 

 of this subfamily the pedicel consists of two highly specialized, nodi- 

 form segments, and the first gastric is the fourth instead of the third 

 abdominal segment, as in the Camponotinae, Dolichoderinse and Poner- 

 mx. In the Dorylinse the genera Eciton and Quietus have a distinct 

 petiole and postpetiole in the worker, but only a single segment, the 

 petiole, in the male and female. In Dorylits and Cheliomyrmex the 

 base of the abdomen of the worker is more primitive and more like that 

 of certain Ponerine ants (Amblyoponc and Ccrapachys). 



The base of the abdomen is the seat of an interesting sound- 

 producing, or stidulatory. organ. Landois, in a book called " Thier- 

 stimmen," published in 1874, was the first to find this organ in a 

 Ponerine ant ( " /Y'm'ri/ quadridentata," probably Ectatomma tjnad- 

 ridciis). He believed that he had seen a similar structure in the Cam- 

 ponotine Lasiits fuliginosus, and a few years later Lubbock ( 18/7 ) 

 figured what he took to be a stridulatory organ in L. flams. Sharp 

 ( 1893 ) and Janet ( 1893/7, i8c)4/? ) have since carefully investigated these 

 organs in several different ants. The former succeeded in finding them 

 only in the Ponerinae and Myrmicime (excepting the Cryptocerii ) and 

 believed them to be absent in the Dorylime, Dohchoderina? and Cam- 

 ])oiiotin;e. The organ (Fig. 12) is best described as a file made of 

 extremely fine, transverse and parallel ridges on a small area in the 

 mid-dorsal, chitinous integument at the very base of the first gastric 

 segment, where it is covered by the overlapping portion of the preced- 

 ing segment. The edge of this segment (Fig. 12, Bp ) is sharp and 



