1889.] 195 



and this would seem to confirm the correctness of his views in attaching 

 great importance to the position of these in the differentiation of 

 species, although he also, for this purpose, relies partly on the number 

 of groups of ventral glands, which no doubt form an important 

 feature. It will be seen that the last five segments have become so 

 much compressed that the real last segment appears almost vertical, 

 with its apex at the top, and at the bottom the two lobes which repre- 

 sent the true lateral margins of the segment, the anus always of course 

 being situated at the apex of the segment. I may mention that the 

 views I have here expressed as regards the supposed terminal seg- 

 ments, I have confirmed by actual observation, so far as Mytilaspis 

 pomorum is concerned ; but to do this, it is necessary to examine the 

 insect in many different moments of preparation, as well-prepared 

 microscopical specimens seldom afford the required evidence of sup- 

 pressed segments. These are more difficult to find in A. nerii, although 

 in this, as in many species, I have traced very suggestive lines. 



The points which I have ventured to bring forward in this paper 

 may be summarized as follows : — 



(i). That all the spinning glands of the Cocczdce are situated on the 

 dorsal margin, and consist usually either of tubular glands, 

 simple csecal openings, or follicles interspersed with cone-shaped 

 villi. 



(ii). That what have been termed " grouped spinnerets " are probably 

 ventral salivary glands, or intestinal glands, possibly analogous 

 to the Lieberkuhn glands or crypts found on the intestines of 

 animals. 



(iii). That what has been termed the last or anal segment, really con- 

 tains five rudimentary segments in the Diaspina, and that 

 similar modifications of the terminal segments are found in the 

 Coccina and Lecanina sub-families. 



(iv). That what have been termed caudal appendages, consisting of 

 lobes, spines, and emarginations, are all indications of the 

 boundaries of suppressed somites. 



I may mention that the works referred to in this paper are : — 



Essai sur lea Cochenilles, par Dr. Signoret (separate edition). 



First Keport to the U. S. A. Dept. of Agriculture, by Prof. Comstock. 



Zur Morphologie und Anat. d. Cocciden, von Dr. Emanuel Witlaczil. 



Studii sulle Cocciniglie, Prof. Targioni-Tozzetti. 



Account of New Zealand Coccidse, by W. M. Maskell. 

 And when referring to any of these authors by name, I have merely mentioned the 

 pages of their work. 



