8(.)0 DAVENPORT ACAUEMV OV NATURAL SCIENCES. 



Oil the front of the head are two or three small conical projections 

 (Hg. 2;^, a) arranged on the median line, that on the extreme front being 

 largest. There is no trace of these on the newly hatched larva, and they 

 are probably left behind with the embryonal skin. Their function is un- 

 doubtedly to open the egg shells, which are always seen to become split 

 open vertically at the anterior end.* 



When the shell becomes split open the young larva makes its exit 

 very laboriously and slowly, undergoing a great amount of wriggling 

 and stretching. On freeing itself from the egg-shell it becomes greatly 

 expanded in length and breadth, and correspondingly depressed in 

 height. During the process of working its svay out of the egg, the tra- 

 cheae become tilled with air, and it is probably at the same time that 

 the buccal sett« are withdrawn from their spiral coils, and form a loop 

 in the abdomen. t 



At fig. 24 is shown an egg of abnormal form containing a fully devel- 

 oped embryo which I observed on June 22d, 1878. Just behind the head 

 of the embryo it was contracted into a neck, giving it an appearance 

 very similar to that of an immature egg follicle. 



The development of the embryo is completed and the birth of the larva 

 takes place within three or four weeks after the eggs are laid, that is to 

 say between June lOth and July 20th. 



[The development of the embryo of Lecan-^-.m hesperidum on oleander, 

 which I have observed incidentally, appears to be almost precisely the 

 same as in this species, except that the eggs remain in the ovaries until 

 hatched. The egg-shell being thinner, more transparent, and without 

 the peculiar ornamentation of the shell above described, it would be a 

 more convenient species to study. The conical "egg-openers" on the 

 head are larger.] 



THE LARVA. 



The young larva, Hg. 2-5, is a little more than twice as long as broad, 

 being at birth about 450 /J. in length and 210 fJ. in bfeadth. It is of an 

 elongated oval form, widest in front of the middle, and with the sides of 

 the abdomen slightly converging posteriorly. It is considerably flat- 

 tened, with the dorsal and ventral surfaces meeting acutely at the 

 margin, which is entire except slight emarginations at the eyes and op- 

 posite each of the four spiracles, and a very deep apal fissure formed by 

 the lobes of the seventh abdominal segment. The margin is furnished 

 with a limited number of slender spines,— six or eight between the eyes, 

 three or four on each side of the thorax, and one on each side of each 

 abdominal segment. At each of the spiracular emarginations is a 

 larger spine, set between two small ones, and at the tip of the ninth ab- 

 dominal segment are six long spines. On the eighth segment are two 



-Dr. A. S. Packard. Jr., det^cribt's aucl figures what ai>pears to he a similar object iu the 

 embryo of Dipla.r, but states that it is "attached to the anterior pole of the shell,'" and 

 supposes it •' to be a micropylc "' Memoiis of the Feahody Academy of Science, Vol. I, No. 

 I r, pp. 3 and 24, PI. II, tis- 13. Salem, 1871'. 



■IDr. E. L. Mark has given a very interestinK account of this process in Aspidiotus nerii 

 iu his Beitrcege zar Anatomie und Histologie des Pflanzenhvuse. page 11,— Bonn, 1876- 



