EMBIA MAJOR FROM THE HIMALAYAS. 



175 



the left-hand portion of the tenth sternum of the nymph participates also in its formation, 

 is extremely doubtful. Prom a prolonged study of the insect, in different stages of 

 development, I have come to the conclusion that the left plate of the 10th sternum 

 becomes modified, hut persists as ventral process (v.p. in PI. 37. fig. 3 and in text-fig. 4). 

 .This process is hinged to the subgenital plate, and is attached to it in the large posterior 



Text-fig. 4. 



'■■&lo. . . 



The three terminal abdominal segments of the adult male, viewed from the dorsal side, b.j., enlarged basal joint of 

 left cercus ; pr.tg. 10, process of the left 10th tergal plate; m.p., median plate; r.p., vestige or rudiment of 

 the process of the right 10th tergal plate; l.tg. 10, left tergal plate of the 10th segment; r.tq. 10, ri"ht 

 tergal plate of the 10th segment ; tg. 8, tergum of 8th segment ; tg. 9, tergum of 9th segment ; v.p. " ventral 

 process," which is probably formed from the left sternal shield of the 10th segment of the larva and nymph. 

 x circa 28. (From a specimen treated with potash and mounted iu Canada balsam.) (Westwood Bequest.) 



concavity, which is shown in PI. 37. fig. 2. Krauss, however, regards this structure as 

 the " Grundplatte " (basal plate) of the left cercus (1911, p. 12). Enderlein (1912) 

 describes it as the " Anhang " of the ninth sternite, which is in accordance with the 

 morphological explanation suggested above. 



The basal joint of the left cercus is sub-conical in shape (PL 37. figs. 2 & 3, and text- 

 fig. 4). Its greatest diameter is at the proximal end and measures double that of the 

 corresponding joint of the left cercus. The proximal surface is excavated to form a 

 prominent concavity (fig. 2), over which are distributed a number of small denticles 

 (text-fig. 4). The inner wall of the concavity is strongly rounded and is situated beneath 



SECOND SERIES. — ZOOLOGY, VOL. XI. 28 



