AHTHTJR DEWITT WHEDOX 391 



"very transparent it was usually necessary to stain the specimens 

 before continuing tbe dissections of parts. 



The description below applies to Lesies unguiculatus unless 

 otherwise noted. The dimensions of this species will be found 

 in the table on pcage 387. 



Alimentary Canal 

 (Plate XXI) 



As the Alimentary Canal is a long straight tube directly at- 

 tached only at the pharjaix and anus its whole course beyond the 

 head must be described. 



The Oesophagus emerges from the occipital foi-amen as a very 

 small, thin-walled tube which immediately expands to a moder- 

 ated diameter (two to three times the diameter of the foramen) 

 and then gradually increases throughout the thorax, in the 

 posterior third of which it becomes pouch-like by ventral enlarge- 

 ment. (Calvert [1915], apparently following Dufour or Sadones 

 seems to limit the oesophagus to the very short cephalic and 

 prothoracic region, the pouched portion then being considered a 

 crop ["jabot" of Dufour and Sadones].) Throughout the thorax 

 it is very thin and, when not distended with air or food, marked 

 with longitudinal creases or folds. Near the union of thorax and 

 abdomen it turns abruptly dorsad in most specimens and after 

 slight constriction enters the crop. This point of union (elbow) 

 is encircled by several apparently muscular cords or very narrow 

 bands, which, lying in a single layer, form a broader band. 

 (Plate XXI, figure 1.) 



A Visceral Sheath (plate XXI, figure 2, vs.) of thin but tough 

 connective tissue completely surrounds the digestive tract from 

 the anterior end of the abdomen to the seventh segment. It does 

 not fit closel}^ the enclosed tube, in preserved material at least, 

 but is of uniform diameter until it reaches the intestine and rec- 

 tum. Here it is not complctcl}' closed over the mid-dorsal line 

 and is more uneven in diameter, and gradually thinning out and 

 disappearing. Its color is brown due to the great number of fine 

 tracheae ,that arise internally from the lateral (ventral, of Till- 

 yard) trunks and form a network upon its surface. It must be 

 opened to expose the abdominal portions of the canal. 



The Crop (plate XXI, figure 1, cr.) extends from the posterioi- 

 part of the metathorax to the suture between the third and fourth 



TRANS. AM. ENT. SOC, XLIV. 



