264 SELECTED NOTES FROM 



Figs. 9 and lo). Mr. Lowne thinks that the maxillae of the Blow- 

 Fly are represented partly by a scale-like portion of the integu- 

 ment bearing stiff set^, from which the palpi arise, and partly by 

 the lateral portions of the operculum, an organ which he defines 

 as consisting of a central portion of the labrum, and the two 

 lateral portions referred to, which he regards as the homologues of 

 the terminal portions of the maxillae of Bees. I would not like 

 to express a very decided opinion on this point, but I have never 

 been able to distinguish any such separation of parts in the 

 operculum as is here indicated. In Figure 7 of my plate the 

 lateral portions referred to are marked x x, as they are also in 

 annexed diagram — ^ ^ from which it will be seen that 



the organ consists /^^^^^^^\ of ^ central tube a, surrounded 

 by an external ^^m'^V^^^ sheath I?. I?., the intervening space 

 being occupied by ^^ ^^ muscles. This being the case, 

 1 can neither find any marked separation into central and lateral 

 portions, nor do I see how it is possible to regard the organ as 

 other than one indivisible whole, viz., the labrum or upper lip. 

 Again, if, as Mr. Lowne says, these lateral portions of the 

 operculum are to be regarded as portions of the maxill?e, where 

 does this hypothesis land us in the Drone-Fly ? For here also 

 that which he calls the operculum, and what I have marked as the 

 labrum in Fig. 9, consists of an internal tube and an external 

 sheath, similar to those in the Blow-Fly, and consequently the 

 lateral portions of the organ here also must by a parity of reason- 

 ing be accounted as the homologue of the maxilla, ie., of organs 

 which are here seen to have a perfectly separate and independent 

 development, being the slender lancets marked w x in the same 

 figure ; quod est absurdiu/i, as Euclid would have said. 



The only thing I can see which gives any colour to Mr. 

 Lowne's theory, is that these lateral portions of the operculum are 

 supported by the anterior extremity of the apodemes, and, 

 therefore may be thought to bear the same relation to them which 

 the maxillae do in the Drone-Fly, in which insect the terminal 

 setaceous portions of these organs are continuous, with a broad 

 internal basal process (shaded in Fig. 4). Now, these basal 

 portions are connected by muscles (;//., Fig. 9) with the anterior 

 portion of the pharynx in very much the same way as are the 

 apodemes of the Blow-Fly, and on this account it is difficult to 

 think that they are otherwise than homologous with those 

 apodomes ; and inasmuch as they are in the one case evidently 

 continuous with the maxillae, and in the other nearly continuous 

 with the lateral portions of the operculum, it may be thought that 

 these latter are really the homologues of the terminal portion of 

 the maxillae. But nearly is not quite, and the difference is well 



