302 ENTOMOLOGTCAI, NEWS [NoV., '15 



the base of the gill, is about one-fifth of that of the gill itself. More 

 posteriorly they are smaller, both relatively and absolutely, and they 

 are not shut off from communication with other spaces. In the caudal 

 end of the proximal joint, the two central blood spaces become con- 

 fluent as one central space, whose vertical diameter is almost as great 

 as that of the gill itself exclusive of the mid-dorsal and mid-ventral 

 carinae. This central blood-space is continued caudad into the distal 

 joint, occupying most of the interior thereof. The chitinous cuticle of 

 this joint is, in these sections, .012 mm. tliick. 



The lateral caudal gill has a dorsal and a ventral longitudinal blood- 

 space near the two longitudinal carinae of the mesal surface, respec- 

 tively. A third appears to run along its lateral or external face. 



A number of resemblances between the internal structure of the 

 caudal gills of Thaumatoneura and those of Euphaea variegata de- 

 scribed by Ris (1912, pp. 171-3) are evident. 



Nerve ganglia. The positions of the ganglia other than the brain 

 are as follows. The frontal ganglion, triangular in shape, with its apex 

 directed caudad (PI. XV, fr), lies on the dorsal surface of the pharynx 

 a short distance (about .15 mm. in larva no. 2) anterior to the brain; 

 it is connected on each side, right and left, with the cerebro-suboesoph- 

 ageal connective. Suhocsophageal ventral to the pharynx, at the level 

 of mid-length of the eyes. Prothoracic in the hind end of the pro- 

 thorax, mesothoracic in the front part of the mesothorax, metathor- 

 acic in the hind part of the mesothorax ; the thoracic ganglia are sepa- 

 rated from each other by intervals shorter than the length of each. 

 First abdominal in the hind part of the metathorax, second in the 

 middle of abdominal segment 2, third to seventh in the front ends of 

 segments 4 to 8 respectively. These positions of the thoracic ganglia 

 are obtained from larvae nos. 2, 4, and 6, of the abdominal from 

 larvae nos. 4 and 6. 



(To be continued) 



Explanation of Plates XV, XVI, XVII. 



Plate XV. Dorsal tracheae and some other organs of Thaumato- 

 neura larva $, no. 4. The dorsal wall of the head has been removed 

 except over the eyes, that of the thorax and of the abdomen has been 

 opened longitudinally to the left of the mid-dorsal line and turned to 

 the right, x 6.1. 



Plate XVI. Diagram of the tracheal supply of the alimentary 

 canal in the hind part of the abdomen of Thaumatoneura larva, dorsal 

 view. X 37.6. 



This diagram has been reconstructed on a horizontal plane from 

 about 850 serial transverse sections from larva no. 7, mounted on 9 

 slides now in the writer's collection at the University of Pennsylvania. 

 To avoid confusing tracheae which lie approximately in the same verti- 

 cal planes, the tracheae are represented farther to right and to left 



