1881.] NATURAL SCIENCES OF PHILADELPHIA. 53 



§ .3. The phan-nx (fig. 51, px.) a strongly miisculav vrall situ- 

 ated within tlie head in front of the neck, nk. 



II. Within the body there is the oesophagus (ce. fig 52), a mus- 

 cular tube^ or canal which passes through the neck and petiole, 

 and connects the head with the abdomen. 



III. The parts within the abdomen, which most concern us are 

 § 1. Segmental Plates of Abdomen. — It is first necessary to 



understand the structure of the wall of the abdomen. This consists 

 of ten strongly chitinous segmental plates, five dorsal and five 

 ventral (PI. Til, figs. 53, 54). These overlap one another, like scales, 

 from the base toward the apex, and the dorsal plates overlap the 

 ventral. The last plates which guard the cloacal cavit}', are 

 known as the pA'gidium (py,) and the h3'pop3'gium (hy.) The 

 anus, in Melliger is surrounded by a circle of strong bristle-like 

 hairs. 



These plates, in the normal condition of the abdomen, are set 

 upon (if I may so say) a strongl}- muscular inner wall, which is 

 highlj^ elastic in all ants, particularly of the Formicida?. This 

 elasticity' appears to reach its extreme point in Melliger. In 

 ordinary excessive feeding, the distension of the crop causes the 

 expansion of the muscular coat between the plates which are thus 

 forced apart, at various degrees of separation, according to the 

 amount of food taken, until in the case of the honey-bearer of 

 Melliger the three middle plates (Nos. 2, 3, 4) are wholl}^ isolated, 

 appearing, as Forel has well said, like little islands on the tersel}- 

 stretched, light colored abdominal membrane. (Plate YII, fio-. 

 54, D2, 3, V2, 3), (Plate X, figs. 72, 73). Plates Dl, Yl, retain 

 their normal position, and plates D4, Y4, are not so wideh' sepa- 

 rated from D5, Y5, as from their next anterior plates. 



We may now view the abdominal portion of the intestinal tract, 

 in order to understand what happens in the growth of the honev- 

 bearer. 



§ 2. The Crop or Ingluvies. — The crop is the anterior and 

 superior sub^division of the abdominal portion of the alimentar}- 

 canal. It is simply an expansion of the (jesophagus within the ab- 

 domen. The normal condition of the crop was determined bv 

 examination of the workers with undistended abdomens, and more 

 readil}' from the stud}' of a virgin queen (PL YIII, fig. 59;, 



'Forel, quoting Meinert, speaks of the muscularization as feeble • but in 

 Melliger, at least, the muscles appear to be sufficiently strono-. 



