Dr. W. Miiller on the Scent-organs in Phiyganidee. 307 



confined to dry material and compelled to give up any inves- 

 tigation of the minute structure. 



In the place of the four extended joints of the maxillary- 

 palpus which we find in the female (fig. 1) , the male pos- 

 sesses a single terminal joint (fig. 2, Mxp) formed by the 

 amalgamation of several joints. It is of a very peculiar form, 

 nearly like a spoon. The margin turned away from the head 

 is dilated inwards and closely applied to the margin of the 

 corresponding joint of the other side. On the other side the 

 spoons lie so close to the head that they seem to form a part 

 of the latter and cover it in front like a mask ; and thus is 

 produced on all sides a very complete closure, which prevents 

 the evaporation of the scented secretion within the spoons. 

 The interior of these spoons is entirely filled with very fine 

 hairs, which originate at the base of the spoons and on the 

 side turned away from the head (of com-se on their inner sur- 

 face). These hairs are pale coloured, slightly clavate, and 

 attain a length of about 1 millim. As already stated, the 

 animal is able to separate and spread out the palpi (how must 

 remain unsettled for tlie present) and at the same time to 

 unfold the tufts of hair. 



Thus we find, as is generally the case in the scent-organs 

 of the Lepidoptera, an enclosure which ordinarily protects the 

 scented secretion from evaporation, and, on the other hand, an 

 arrangement by which at the proper moment a large surface 

 is presented for evaporation, so as to effect a great develop- 

 ment of the scent. 



In the Phryganidee there are pretty frequently secondary 

 sexual characters, and it seems not improbable that fre- 

 quently, or at any rate in some cases, these have to do with 

 scent-organs. I may refer in the first place to Notidohia *, 

 in which, according to Brauer, the maxillary palpi are boat- 

 shaped and stand in the same relation to the forehead as in 

 Sericostoma^ and, further, to Asjpatherium f, in which the 

 maxillary palpi in the male are short and strongly hairy, 

 although not dilated. In l^cclisojiteryx and Halesus\ there is 

 in the male at the base of the hind wing a folded pouch with a 

 pencil of hairs. A similar sac occurs, according to MacLach- 

 lan §, in the genus Drusus. Further, Fritz Miiller states that 

 on the maxillary palpi of the male Grumichce there are hair- 

 tufts which probably serve as scent-apparatus, as also '' that 

 in the wonderful antennae of the males of Peltopsyche he is 

 inclined to see scent-apparatus." 



* Brauer, ' Neuroptera Austriaca ' (Vienna, 1857), p. 43. 

 t Loc. cit. p. 42. X Loc. cit. pp. 46, 47. 



§ MacLaclilan, ' Revision of European Triclioptera,' p. 164. 



