fi,EMARKS ON CERTAIN GENERA OF COCCID^. 167 



The main reason for considering the three insects named as 

 belonging to one species is tlie character of the epidermal cells ; 

 and I may quote here the expressions thereon of the authors 

 mentioned. Previously, however, we may discard an external 

 character referred to Ijy Signoret, — "dorsum slightly elevated, 

 with two small depressions in specimens from Italy and two 

 carina in specimens from France," — because evidently this is not 

 a constant character. As regards the epidermis, Signoret says 

 of L. depressam : — "Exhibiting a great number of tessellated 

 irregular plates forming a marquetry pattern ; each plate has a 

 darkish band round it, with a clearer but still rather dark 

 surface-space and a central clear space with a small orifice." 

 And in his Plate 13, fig. 11a, he delineates the cells as 

 irregularly polygonal. 



Douglas says of L. nigrum : — "Under the microscope the 

 whole surface is seen to be covered with a tesselation of closely 

 approximate small yellow dots and punctures " ; but he does 

 not specially mention their form. 



Douglas says of L. depressum: — "Surface covered with a 

 reticulation of irregular shallow cells with a pale centre or 

 ocellus." 



Douglas says of L. hegonm : — "Covered with contiguous, 

 minute, oval, yellowish dots." 



Green, Targioni, and Nietner make no mention of the 

 epidermal cells. 



It seems clear here that Mr. Douglas agrees with Dr. Signoret 

 as to tbe irregular form of the cells in L. depressum, but his 

 language leads one to think that he considers those of L. nigrum 

 and L. begonice to differ in being more dot-like and oval. 



But, on further consideration, it is doubtful whether Mr. 

 Douglas made any examination of the epidermis except an 

 external one (that is, viewing the insect in sitii, without pre- 

 paration). For although, examined in this manner, a certain 

 (though by no means a great) difference seems to exist in the 

 cell-forms, yet closer observation by transmitted light shows that 

 in reality they are identical. The cells of L. nigrum and L. 

 begonice, which at first sight appear more or less oval, are then 

 seen to be very clearly polygonal and irregular, and to form what 

 Mr. Douglas says of L. depressum, a " reticulation." In some 

 specimens of L. begonice I find the cells perhaps rather smaller 

 than usual ; but as a rule, in all three insects, the average 

 (longest) diameter of a cell is about the same, l-500th of an inch. 

 The outer band and the central orifice are visible in all. Perhaps 

 the cells in L. begonice may be the darkest in colour. 



Looking therefore at the epidermis, it appears sufficiently 

 clear that the three insects are identical ; while in size, colour, 

 and generally convex form, they also agree. Mr. Douglas, 

 indeed, says that some of bis specimens of L. depressum were 



