Structure of Scent Organs in Male Danaine Butterflies. 169 



appearance. A section through a portion of the pocket 

 is shown at PL XX, fig. 29. The cupped glands contain a 

 comparatively small cell, finely granular and possessing 

 a large nucleus. From each arises a delicate projection 

 which is doubtless a degenerate scale. From each un- 

 modified socket arises a scale, and they are sufficiently 

 numerous to form a complete lining to the pocket. These 

 scales are porous, the minute openings lying along the 

 striations of the surface mainly in the central area of the 

 upper side. In connection with each scale is a large cell, 

 the upper part of which is densely packed with large and 

 conspicuous granules having a deep brown colour in un- 

 stained examples. These coarse granules usually obscure 

 the nucleus which is also present in the upper half of the 

 cell. They do not dissolve in ether, alcohol, or xylol, and 

 are only very slowly aftected by eau-de-javelle. The 

 remainder of the cell is occupied by a delicate and highly 

 vacuolated reticulum, presenting a finely granulated 

 structure. Whether the hair-like vestigial scales arising 

 from the cupped cells are open tubes or not I have been 

 unable to decide. The covers of the cups have, however, 

 rather the appearance of being minutely perforated, though 

 this point is also extremely difficult to decide. 



It should be noted that the structure described above, 

 in so far as it consists of special scales alternating with 

 delicate stalks, is similar to that described by Miiller as 

 occurring in D. erippus* 



Paralitica eryx, Fab. 



This species bears on the hind-wing a scent-patch of 

 considerable size and presenting a somewhat pear-shaped 

 outline. In surface view it shows regular rows of scent- 

 cups alternating with normal scale-sockets from which 

 arise scales much resembling those of Amauris niavius in 

 shape, though rather larger. They form a continuous 

 covering for the scent-patch of which a section is shown 

 at PL XIX, fig. 17. Perhaps the most striking features of 

 the patch are its comparative thinness and the large number 

 of nuclei observed in each gland. In some cases I have 

 counted as many as seven. Whether this number indicates 

 the presence of seven cells, or whether some cells have 

 more than one nucleus, has not been determined. There 



* See my previous paper, Trans. Ent. Soc. Lond., p. 403, 1913. 



