i5G Mr. B. B. Woodward on the 



as well as at the apex of the antenna, a few very mu^li 

 smaller hair-like structures somewhat similar to those to 

 which an olfactory function has been usually ascribed. One 

 of these, in close proximity to the organ in question, and two 

 at the apex have a shape somewhat like that of a hand-bell. 

 The remaining two at the apex are more or le?s cylindrical, 

 with rather blunt extremities. Another on the third segment 

 is shorter and broader and seems to have the form of a trun- 

 cated cone. 



It may be mentioned, in conclusion, that the presence of 

 the " appendix " is not confined to the larva3 of a few 

 genera of beetles. According to the observations of ychiodte 

 and of Chapuis and Cand^ze it seems to be characteristic 

 of the larvae of Carabidaj, of Chiysomelidse, and of certain 

 other large families of Coleoptera, and that, though usually 

 placed towards the outer or posterior side of the distal surface 

 of the penultimate segment, it is, in the Staphylinidas, situated 

 on the anterior side. 



The only other species in which I have had an opportu- 

 nity of examining it was one of Telephoriis, in which it had 

 the same relation and pretty much the same general structure 

 as in Pterosti'chus, the chief difference being that the chitinous 

 ring, instead of having a uniform width throughout, is narrow 

 at one side and extends upwards, to reach its greatest width 

 on the opposite side. It was first noticed in this larva by the 

 late G. R. Waterhouse, who referred to it as a " process." 



Considering, therefore, the widespread existence of this 

 appendix amongst Coleopterous larva3, and of its very definite 

 localization on the penultimate segment of the antennee, 

 togetlier with its ratlier peculiar structure, it seemed to me 

 that some elucidation of its precise nature and meaning was 

 desirable. And even should it ultimately be proved that I 

 have been mistaken in my first observations upon it, there 

 will be some justification for having directed attention to a 

 structure which seems to have been hitherto almost entirely 

 neglected. 



XX. — Classification of the Pelecypoda : Fischer^ s Families 

 rearranged in accordance with. Pelseneer'' s 8cheme. By B. B. 

 Woodward, F.G.S., F.R.M.S., of the British Museum 

 (Natural History). 



The classification of the Pelecypoda has been from the first a 

 matter of great difficulty owing to their comparatively uniform 

 structure. 



The characters hitherto employed have been more or less 



