384 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 1 37 



by the second maxillae which unite to form the labium. This cavity 

 is formed when the embryo is ready to hatch. Uzel also describes 

 how both the first and second maxillae undergo rotation, as follows : 

 Simultaneously with the first appearance of the fold the anlage of 

 the first maxilla divides into an outer and an inner part ; immediately 

 afterward, when the anlage of the hypopharynx is appearing, the 

 outer one turns forward in an oblique position to the inner one, then 

 divides into two, the lobus externus and the palpus, and then returns 

 to its original position. The second maxilla undergoes the same 

 division and rotation, but before the first maxilla has returned, the 

 second maxilla is back again and even continues this rotation so that 

 the lobus externus finally lies anteriorly to the palpus. (Denis, 1949. 

 p. I Si, will not admit this interpretation, according to which the palpi- 

 form lobus of Carnpodea is not the palpus as in Japyx, but the lobus 

 externus ; Bitsch, 1952, however showed it to be an indigenous struc- 

 ture of Carnpodea. Bitsch also doubts the existence of the rotation 

 seen by Uzel, but I do not quite see why.) 



It is important to notice that the figures in Uzel show the head of 

 the embryo seen from in front, that is to say that one cannot see the 

 length of the mouth parts. Silvestri in 1933 describes minutely the 

 development of the mouth parts in Prof japyx maior, but he too, in 

 most of his figures, depicts the head as seen from in front. The de- 

 scription of the plicae orales is exactly as in Carnpodea, and from his 

 figures it appears that a similar, though less pronounced, rotation of 

 the first and second maxilla takes place. In his figures II5 and IIIi_2, 

 however, the head is seen in a more ventral or lateral view, and from 

 these it appears that before the rotation of the second maxilla the 

 mandible does not proceed farther backward than the first maxilla, 

 as is the case in the adult animal. Unfortunately, figure Ills, of the 

 head of the prelarva (the last stage in the Qgg), does not show the 

 mandible. 



Prot japyx (Silvestri, 1933 and 1948) emerges as a first-stage larva, 

 "larva primae aetatis," which, however, is nearly immobile and yet 

 lasts 5 to 6 days, when after a moult it develops into the second larval 

 stage, also nearly immobile and morphologically different from the 

 following stages. Carnpodea (Orelli, 1956) emerges as a prolarva, 

 which lasts only a few minutes and then develops into a larva neonata, 

 both morphologically different from the following stages. The pro- 

 larva and the larva neonata in Carnpodea seem to correspond to the 

 larvae primae and secundae aetatis in Protjapyx. The first larval 

 (prolarval) mouth parts of Protjapyx are figured and described by 

 Silvestri (1933, p. 335 and fig. III0-9) ; the mandibles have only two 



