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VIII . On the external sexual apparatus of the males of the 

 genus Acentropus. By Robert M'Lachlan, 

 F.L.S., Sec. Ent. Soc. 



[Read 1st April, 1872.] 



At the Meeting of this Society held on the 4th ultimo, 

 my friend Mr. Dunning read a memoir (see preceding 

 paper) on the genus Acentropus, which I propose to sup- 

 plement by some remarks of my own, on points avowedly 

 not investigated by him. Of the ordinal position of the 

 genus I say nothing, except that I thoroughly agree with 

 those entomologists who place it in the Lepidoptera, feel- 

 ing sure that the few who appear to doubt the correctness 

 of this opinion, can never have studied the characters, or, 

 if they they have done so, maintain a factious opposition 

 from pure affectation. As a Trichopterist, I assert that the 

 attributes of the genus, its structure, larval characters, 

 and, in fact, everything excepting its aquatic habits, are 

 utterly opposed to its being Trichopterous, whereas there 

 is nothing whatever incompatible wiLh its ordinal position 

 in the Lepidoptera. 



Before proceeding to the subject of this paper, I will 

 remark, en passant, concerning Mr. Dunning's observa- 

 tions regarding the existence or non-existence of ocelli. 

 Kolenati asserted the presence of two undoubted ocelli 

 in the ordinary position on the front portion of the vertex. 

 I have no hesitation in declaring these ocelli to be fic- 

 tions. At a seance alluded to by Mr. Dunning (see 

 p. 129) at which he, myself, and Mr. Douglas were 

 present, we subjected several examples to minute mi- 

 croscopic investigation, after having carefully denuded 

 the heads of every vestige of scaly clothing. The result 

 proved that in the position assigned by Kolenati, there 

 were no signs whatever of ocelli either developed or 

 abortive. But, in a slight depression on the outer side 

 (that next the eye) of the base of each basal joint of the 



TRANS. ENT. SOC. 1872. — PART II. (mAY.) 



