808 . Jill. .T. O. H. FEISW ON XUIJ; LAKVAL 



dorsal line and the ventral ones in the mid-ventral line, so that 

 when the imago emerges the whole of the thoracic region of the 

 pupariiun falls oft' in two halves. Usuall}^ the ventral splits are 

 longer than the dorsal. When the puparinm splits the larval 

 spiracles are situated on the dorsal lialf of the split thorax, very 

 slightly dorsal to the split. 



The First Larval Instar is extremely similar to the third instar. 

 The head and cephalo-pharyngeal skeleton are identical in form 

 to those of the third instar; the arrangement of the tracheal 

 trunks is tlie same, but the smaller hra.nches of the tracheal 

 system ramify less extensively, many being either not yet formed 

 ov not tilled with gases so as to be visible. On emergence from 

 the ^g*^ the larva is completely apneustic. The dorso-lateral 

 tracheal trunks extend from the anterior region of the second 

 body-segment to the posterior region of the eleventh body- 

 segment. Tliere is no indication Avhatever of anterior spira.cles. 

 Posteriorly, in the position occupied in the second and third 

 instars by the posterior stigmatic papilla), there are two stout 

 and prominent papilke with a truncated apex. These show no 



Text-fionre 12. 



C. tcenidjms. Lateral view ol: empty pupiiviuni. 



trace of stigmatic openings, and the dorso-lateral tracheal trunks 

 do not extend into them ; four rather stout pointed setse radiate 

 outwards from the dorso-lateral border of the apex of each of 

 these papillae. 



In the first larval instar there is no difference in shape between 

 the thoracic and abdominal denticles, all being of the approxi- 

 mately semicircular shape found on tlie abdominal segments of 

 the third instar. Their distribution is slightly different from 

 that in tlie third instar in that they do not appear to extend 

 into the dorsum of the thoracic segments. Such cha,racters as 

 these, however, require very careful examination with an oil 

 immersion. I have not yet succeeded in finding the vestigial 

 leg-sense organs in tlie first instar ; if they a,re present, however, 

 they will naturally be extremely minute, and T. am not, thei^efore, 

 prepared to say definitely tliat they are .absent. 



Maximmn lengtli of cephalo-pharyngeal sclerites _ .11 • ,1 

 Maximum dorso-ventral depth of sclerites ~ 



tliird larval instar and about 4^ in the first larval instar. 



