A. J. Grove 
25 
lying between the egg-tubes. It has also been termed the “ Pseudo- 
vitellus.” I have been unable to determine any definite distribution 
for it, and the quantity varies in different specimens. 
Structurally, it is made up of very large cells (Plate I, Fig. 24) with 
well-defined nuclei, and the granular cell contents resemble very greatly 
the yolk of an ordinary insect egg. 
Witlaczil (1882) attaches an excretory function to it, but both from 
its position and structure it is more likely to be nutritive in function. 
Circulatory System. 
I have been unable to find any structure which would answer to a 
dorsal vessel or heart in S. rosarum, and it is probable that any blood 
system which may be present consists of a series of haemocoeles. 
LITERATURE. 
Buckton, G. B. (1875—1882). A Monograph of British Aphides. Ray Society 
publication. 
Drefus, L. (1894). Zu J. Krassilstschik’s Mitteilhungen iiber “die vergleichende 
Anatomie und Systematik der Phytophthires ” mit besonderer Bezugnahme auf 
die Phylloxeriden. Zool. Anz. xvn. pp. 205—208, 221—235, 237—242, 2 pis. 
Dufour, Bison (1833). Recherches anatomiques et physiologiques sur les HemipRres. 
Flogel, J. H. L. (1904). Monograpbie der Johannisbeern Blattlaus. Aphis ribis. 
Allg. Zeitsckr. Ent. ix. pp. 321—333, 375—381. 
Flogel, J. H. L. (1905). Monographie der Johannisbeern Blattlaus. Aphis ribis. 
(Continuation and Conclusion.) Zeitschr. Insbiol. i. pp. 49—63, etc. 
Krassilstschik, J. (1892). Zur Anatomie der Phytophthires. Zool. Anz. xv. 
pp. 217—203. (Summary in Journ. Roy. Microscop. Soc., 1892, p. 781.) 
Krassilstschik, J. (1893). Zur Anatomie und Histologie der Phylloxera. Horae 
ent. Ross. xxvn. pp. 1—37, pis. i—ii. 
Krassilstschik, J. (1893). Zur vergleichenden Anatomie und Systematik der 
Phytophthires. Zool. Anz. xvi. pp. 85—92 and 97—102. 
Mark, E. L. (1877). Beitrage zur Anatomie und Histologie der Pflanzenlause 
insbesondere der Cocciden. Arch. f. mikrosfcop. Anat. Bd. xm. 
Mayer, P. (1874—5). Zur Anatomie von Pyrrhocoris. Arch. f. Anat. u. Physiol., 
1874, p. 313 ; 1875, p. 309. 
Mordwilko, A. (1895). Zur Anatomie der Pflanzlause. Zool. Anz. xvm. 
pp. 345—364, 402. 
Mordwilko, A. (1896). [Summary of paper by this author on the Anatomy of 
Trama and Lachnus.'] Zool. Centralbl. iv. pp. 72 — 75. 
