90 CLAUD P] FULLER. 



Fig. 21a. — The system of the newly-hatched young of Crypto- 

 termes as seen from below. It illustrates the early arrangement of 

 the ventral longitudinal trunks linking up the ventral commissures; 

 the anastomosis of the cervical with the first ventral commissure ; the 

 commissure linking up the two ventral trunk trachea* of the head ; 

 the trachea? of the mouth -parts. (The routes of the paired trachea? of the 

 labrum are indicated by dotted lines. The palisade commissures and 

 the dorsal longitudinal trunks being the same as those in the meta- 

 termite stem, are omitted). 



Fig. 21b. — The dorsal trachea? of the head of Cryptotermes, as 

 arranged in the second stage of their development. (The trachea? of the 

 vertex and gena? are shown in solid black). 



Fig. 21c. — The dorsal trachea? of the head of Cryptotermes, as 

 seen in the newly-hatched young. 



Inset : The mandibles of the nymph of Eutermes sp., showing how 

 both are composed of three well-defined regions. 



PLATE V. 



Figs. 22a to 22h. — These figures show the development of the pipes 

 of the thoracic sjDiracles from enlarged tubes to air-sacs, figs. 22a to 

 22e being of the first pair, and figs. 22f, g, h of the second pair. All 

 are proportionately enlarged except fig. 22e. which is drawn upon a 

 smaller scale. The conditions represented by figs. 22f and g accompany 

 the conditions of the first spiracle in figs. 22a to D ; fig. 22h of the 

 second spiracle accompanies the condition seen in fig. 22e of the first 

 spiracle. All figures are from camera lucida sketches of nymphs of 

 Microtermes incertus. The bases of the tracheae shown are in 

 figs. 22a to 22e those of: (1) The dorsal trachea of the head which 

 tei'minates in tlie tip of the antenna; (2) the stem of the U-shaped 

 ventral trachea of the head which bears tlie tracheae of the mouth- 

 parts ; (3) the trachea of the first leg ; (4) the ventral commissure of 

 spiracles I ; (5) the traciiea to the second spiracle. In figs. 22f. g, h 

 they are the bases of (1) the trachea to the first spiracle; (la) the 

 trachen to the third (or first a1)dominal) spiracle ; (3) the ventral com- 

 missure of spiracles II. 



Figs. 23a, b, c. — These figures illusti-ate the iipparent arrangement 

 of the abdominal series of spiracles (spiracles III to X as seen from 

 within) in the newly-hatched young of T. natalensis and T. lateri- 

 cius. The features shown are : (1) The circular pore or fixed opening 

 in the cuticle ; (2) the atrium ; (^a) the vestigial resister ; (3) the lever ; 

 (4) the epitrachelos ; (5) tlie trachelos; ((5) the tracheal j)ipe; (oc. m.) 

 the occlusor ; {ex. in.) the extensor muscle. 



Figs. 23a and B show the spiracle open and 23c closed. In 23b the 



