DESCRIPTION OF PLATE I. 



pseudovuiii of Chermes laricis, hardened previously by 

 weak alcohol. The young are to be found here in a 

 very perfect condition of development ; the antennae 

 are well articulated, and the three remarkably long 

 rostral setae are very conspicuous. This specimen 

 was taken from a pale yellow egg, which had not been 

 much darkened by exposure to the air, and probably, 

 therefore, it had been recently deposited. It may 

 perhaps be inferred that, as the young in these eggs are 

 in so forward a state just at the time of laying, there 

 is some approximation to the ordinary viviparous 

 production of the unfecundated egg. I have not been 

 able to discover the fecundated egg (the true ovum) 

 of Cltrrmrs ; but we know that in allied genera of 

 Aphis it is very large and often single. The (pseudo-) 

 ovarian caaca of Chermes probably amount to one 

 hundred. 



Fig. 11. — Embryo from the pseudovarium of Aphis 

 pelargonii, reduced from Prof. Huxley's figure and 

 seen in profile : e, alimentary canal, taking a curved 

 form and ending at the anus a; lb, labruni ; <in. 

 antennas ; /, /', I", first, second, and third pair of legs ; 

 ps, rudimentary chambers of a foetal pseudovarium ; v, 

 vitelline mass. 



Fig. 12 — Horny ring and armature on the apical 

 segment of the male of Lachnus pinicola. They 

 would appear by their contraction capable of embracing 

 and rendering tense the organ when active : a, arma- 

 ture; c, lower plate; p, part of penis. 



Fig. 13. — Similar parts in front view, from the 

 male of Galli/pterus querv&s. 



Fig. 14. — Last apical segments of the male of 

 Aphis dirltoil't, showing the genital organs in situ, u, 

 anus; c, Cauda; d t clasper; p, penis; n, cornicle; 8, 

 stoma ; t, testes ; m, muciparous glands. 



Fig. 15. — Upper and lower portions of the alimen- 

 tary canal of Lachnus r! niinnlis, showing the manner 

 in which tho walls are encased with broad epithelial 

 plates. 



