78 Proceedings of the Royal Irish Academy. 



somewhat similar sacs have since been described by Endevlein ('99, Taf. i, 

 fig. S) in the larva of Cdbbi pTiantis. 



In front of the tubes so far mentioned, there are given off from each main 

 trunk two outer tubes corresponding with the first and third anterior connec- 

 tives (which we believe to belong respectively to the mesothorax and the first 

 abdominal segment) in the same way as the rest of the abdominal outer tubes 

 correspond with the inner ones of the same segments. From this it seems 

 likely that these latter may be derived from original transverse connectives 

 which have lost their direct continuity. There are apparently no outer tubes 

 corresponding with the second (metathoracic) of the three anterior connectives 

 (fig. ",".'•. 2). The outer tubes in front of the second abdominal have no 

 connexion with any lateral Bpiracles, uor do they divide into definite inner 

 and outer ramifications : they break up into a number of fine tracheae, those 

 from the foremost branch going to the sucking pharynx. Of the three 

 anterior transverse connectives, the second and third respectively give oil two 

 and eight branches which run forwards (fig. 3. ". c. 2, 3). The main longi- 

 tudinal trunks are continued forwards as plugged tracheae which lead to the 

 anterior spi r described in detail below. 



Thk Lateral Spiracles and tiif.ii: Tracheal Connexions. 



pairs ol ngly minute lateral spiracles situated on the 



nd to the seventh abdominal - inclusive (figs. 1, 2, 3, 1. «.). The 



cuticle of the larva is divided into broad dorsal and ventral areas, which are 

 _ ither Bide "i the body by three longitudinal areas, marked on 

 most of the segments by projections or Bpinose bosses; these three regions 

 ma;. . i as the doi so-lateral, lateral, and ventro-lateral areas 



i.d.l., /.. v. I.). The l.u teles are situated on the smooth cuticle 



A-een the lateral and ventro-lateral areas near the anterior border of 

 each segment. Viewi ally figs. 4-6) the spiracle appears as a small 



aperture among the scale like areas of the superficial cuticle. On the fifth 

 abdominal > c I >r example (tic. 4. iv), there is a simple cup-like depres- 



sion, surrounded by a smooth zone [ .it ing crack-like markings. In 



the case of the spiracles at the front and hinder ends of the series (figs. 

 4. i. ii. vi, 5) the cavity is seen to be overhung with a thickened edge of the 

 scale-like area of the cuticle. Viewed from within the body-wall, through the 

 tiansparent substance of the secondary cuticle, such a spiracle (fig. 0) has the 

 apj>earance of a conical cavity, one side of which is strengthened by a curved 

 ridge of dense chitin (fig. 6, r. /•. ). The surface-markings (fig. 6, m.) around 

 the spiracular cavity and the scale-like areas of the outer surface are visible 

 through the secondary cuticle. 



