54 PROCEEDINGS OF THE ACADEMY OF [1881. 



The ocspliagiis ce, is there seen passing through and bent over 

 the hard ring (J71) which forms the junction of the petiole and 

 abdomen. The oesophagus is seen as continued (ce c) within the 

 abdomen, where it has precisely the same structure as within the 

 thorax. The crop or ingluvies contains a moderate amount of 

 food and is fairl}^ distended. The exterior coat of the crop is a 

 net-work of muscles which present the branched character some- 

 times found in insects (PI. VII, fig. 45). Another section of the crop 

 showing tlie character of this muscularization is given at 

 Fig. 46. This enlarged view is taken from the object shown at 

 PI. YIII, fig. 55, and is made at the margin. The spherical crop 

 is thus seen to be hung within the muscular netting, something 

 like an inflated balloon within its net bag. 



Forel thinks^ that the muscles of the segmental walls of the 

 abdomen alone are concerned in the act of regurgitation; but I 

 see no ground for this opinion, except possibly with the honey- 

 bearers, whose abdominal muscles alone might suffice to expel the 

 contents of the crop. Such a remarkably efficient structure as is 

 here demonstrated and illustrated, can hardly be without its proper 

 function. 



Before proceeding to demonstrate the main point in hand, it 

 will be well to follow the alimentary canal to its termination. 



§ 3. The Gizzard or Pboventriculus. — The crop is continued 

 posteriorly by the gizzard, gz (PI. VIII, figs. 55, 56, 57, 59), a 

 singular and complicated organ in ants which has given rise to 

 conjectures the most diverse. Meinert regards it as serving to 

 regulate the movement of the aliments. Forel thinks it certain 

 that it serves above all to close, and for the most part hermeti- 

 cally, the digestive canal between the crop and the stomach.- The 

 gizzard properly belongs to the anterior part of the intestinal 

 canal its internal cuticle (tunica intima) being a direct continua- 

 tion of the crop, oesophagus, pharynx and mouth. It consists in 

 Myrmecocystus (and the entire sub-family Camponotidse) of three 

 parts. 



^ Swiss Ants, p. 111. 



^ The gizzard varies largely among ants, and the variations form generic 

 characters of great value, which Dr. Forel has shown, first in his ' ' Four- 

 mis de la Suisse," p. 112, seq., and afterward, more fully and clearly, in his 

 "Etudes Myrmecologiques," Bulletin de la Soc. Vaudois d. Sci. Nat., Vol. 

 XV, 1878,pp. 337, 392. This last study of this organ is one of the most 

 admirable contributions yet made to niyrmecological histology. 



