74 Transactions. — Zoology. 



made in my paper of 1892, when I reported L. deprcssum 

 from Sydney and Honolulu, for I had then in my possession 

 the same material, but having many other things to think of 

 I overlooked the point. 



The main reason why I consider the three insects named 

 as belonging to one species is the character of the epidermal 

 cells ; and it is necessary to begin by quoting the expressions 

 thereon of the authors mentioned, who have spoken of them. 

 Previously, however, we may discard an external character 

 referred to by Signoret — " Dorsum slightly elevated, with two 

 small depressions in specimens from Italy, and two carinoe in 

 specimens from France " — because evidently this is not a 

 constant character. As regards the cells of the epidermis, — 



Signoret says of L. dejyi-esstim, " Exhibiting a great num- 

 ber 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 pi. 13, fig. 11a, he delineates the 

 cells as irregularly polygonal. 



Green, Targioni, and Nietner make no mention of the 

 cells of the epidermis. 



Douglas says of L. nigrum, " Under the microscope the 

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

 approximate small yellow dots and punctures " ; but he does 

 not make any observation as to their form. 



Douglas says of L. deprcssum, " Surface covered with a 

 reticulation of irregular shallow cells with a pale centre or 

 ocellus." 



Douglas says of L. hcgonicB, " Covered with contiguous, 

 minute, oval, yellowish dots." 



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

 Signoret as to the irregular form of the cells in L. dejjressum, 

 but that he considers those of L. nigrum and L. hegonicB to 

 differ in being more " dot-like " and oval. Indeed, he remarks 

 that the two last insects seem to be very similar to each other. 



But, on further consideration, it seems doubtful whether 

 Mr. Douglas made any examination of the epidenuis except 

 an external one (that is, viewing the insect in situ, without 

 preparation) — for although, examined in this manner, a 

 certain (though by no means a great) difference seems to 

 exist between the cell-forms, yet closer observation by trans- 

 mitted light shows that in reality they are identical. The 

 cells of L. nigrum and L. hegonice, 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. depres- 

 sum — a " reticulation." In some specimens of L. hegonice I 

 find the cells perhaps rather smaller than usual ; but, as a 

 rule, in all three insects the average (longest) diameter of a 



