Ixxix 



disc is almost non-existent, being reduced to a hardly per- 

 ceptible dilatation of the proximal end of the footstalk. 



" These points are all easily visible in the drawings exhibited, 

 which represent the clasper and scent-scale of the male B. 

 gidica, compared with the corresponding structures in other 

 species of Belenois. 



" So far, however, as neuration goes, gidica might well be a 

 Belenois. It is also worth noticing that its larva, like that 

 of at least one other species of Belenois, is stated to feed on 

 Capparis." 



In the course of the discussion that followed Dr. Dixey's 

 remarks, Commander Walker said that Belenois teutonia 

 feeds on Capparis, and Dr. Marshall said that B. mesentina 

 has the same food-plant in South Africa. 



The tympanal organ of Speiredonia (Noctuidae). — 

 After having described the special abdominal tympanal 

 organ which characterises the noctuiform families of moths, 

 and drawn attention to the great diversity obtaining in the 

 development of this organ within the families. Dr. Jordan 

 said that in those Noctuid genera in which the first abdominal 

 pleurum forms a large lobe or dome over a deep tympanal 

 cavity the first stigma is found within the cavity, while in 

 the species of the allied families with a similarly large dome 

 (often resembling a bladder in dorsal aspect) the stigma is 

 j)laced on the outer surface of the pleurum, visible in a lateral 

 view of the abdomen. In Speiredonia and some allied Noctuids 

 a specialisation obtains that is worth recording. As a rule 

 the Noctuids have, in the cavity, a vertical ridge in front of 

 the stigma, the ridge being often a mere line, but sometimes 

 enlarged into a long lobe. In Speiredonia the ridge is moder- 

 ately raised, and its edge is drawn out into a row of hair-like, 

 branched processes which project forward over the inner 

 jjortion of the tympanal cavity and almost touch the thorax. 

 These false hairs are fairly stiff and end in very thin points. 

 The hedge thus formed may possibly serve as a guard against 

 the penetration of foreign bodies into the deep recesses of 

 the cavity where the delicate tympanal membranes are found ; 

 but it appears more likely that the filaments are a means of 

 increasing by their vibration the strength of the sound-waves. 



