17 



has been bred by Mr. Pergande and is a marvelously beautiful insect, 

 with two large abdominal brushes which it spreads like the tail of a 

 peacock. It has prominent faceted eyes, a long, slender penis, and four 

 hooks on the rudimentary hind wing. Its structure is that of a male 

 Coelostoma. The transformations to the adult stage in both sexes 

 probably take place iu the spring and early summer. In the winter 

 the only living forms to be found are in the encysted stages under the 

 bark. The insect has at this time a disagreeable odor of rancid fat. 



These remarkable transformations are not without parallel in the 

 Coccidas, although the full life history has never, to my knowledge, 

 been worked out in any allied form. _ In Porphyrophora and Marga- 

 rodes there is a similar retreat into an encysted stage, with reappear- 

 ance of the organs of locomotion in the adult female when it breaks 

 forth from its subterranean pearl. The transformations of the male in 

 these genera have never been made known and the winged male is 

 known in Porphyrophora only. In certain forms from New Zealand 

 and Australia, for which Maskell erected the genus Coelostoma, very 

 similar changes occur in the female series, although I am not sure that 

 in any of the described species a complete absence of all legs and 

 antennas has been noted. In Coelostoma zealandicum, the type of the 

 genus, described in Trans. N. Zealand Institute for 1879 (Vol. XII, p. 

 291), and also in the same Transactions for 1881 (p. 226) and 1883 

 (p. 141), Maskell describes the second stage of the female as having 

 partially atrophied feet and antennas; and in his Coccidas of New Zea- 

 land (Plate XX) he figures a spiracle of the female with a constricted 

 neck and ring of pores, and also an anal u honey-dew organ," which 

 evidently has a similar construction to that seen in our coccid from 

 birch. Again, in the New Zealand Transactions for 1889 (p. 153), Mas- 

 kell describes and figures (PI. IX, figs. 19-22) precisely similar internal 

 organs in Coelostoma assimile, and states that the female of the second 

 stage is globular, with conical four-jointed antennas and without feet. 

 The insect in this stage is covered with a hard waxy test, and is found 

 in the axils of twigs of Fagus. Finally, in 1882, F. Loew (Verhandl. 

 d. k. k. Zool.-Bot. G-es., Band XXXII, Taf. XVI) describes and figures 

 under the name Xylococcus filiferus a coccid which he found buried in 

 pits in the axils of twigs or buds of linden at Baden, Austria. His 

 figures indicate a form very closely allied and probably congeneric with 

 the birch coccid of which we have been treating. But in his descrip- 

 tion Loew considers as the mature stage what is evidently one of the 

 legless intermediate forms of the female, and details the issuing of 

 the young from this form as from a viviparous adult. The manner in 

 which this mistake may have been made and the true egg-producing 

 female overlooked has been sufficiently indicated above. Loew more- 

 over figures and describes as the second stage of the female a form 

 having antennas, but with legs represented by coxas and trochanters, 

 which corresponds in every respect to the encysted second larva of the 

 8193— No. 18 2 



