220 Linnean Society. [May 3, 



had again been directed to the peculiarities of the organs of vision 

 in the male sex. He had already shown that these individuals pos- 

 sess only ocelli at the sides of the head as well as on the vertex, but 

 that these structures exist at precisely the same parts of the head as 

 the ocelli and the compound eyes in the female, and consequently 

 that there can be no doubt of their homology. These appearances, 

 however, having led some to question the correctness of this, it be- 

 came necessary, in order to judge aright of their nature, to consider 

 what are the essential conditions of a structure which is specially 

 destined for the appreciation of light. This consists, as already 

 pointed out in Fishes, of a follicle or pit in the tegument of the head, 

 coated with dark pigment, and receiving the distal termination of 

 a particular cerebral nerve, conditions which are precisely those of 

 the ocelli, both of the sides of the head and of the vertex, in Antho- 

 phorahia. The various modifications of the eye in insects, with re- 

 gard to the form of the cornea, the depth of the chamber, and the 

 presence of the choroid, and of the lens, with reference to the extent 

 of field, and the focal distance, of vision, were pointed out, and the 

 degree in which they exist in Anthophorabia mentioned, as coinciding 

 with the peculiar habits of the insect. The structures in the male 

 were thus shown, by the presence of cornea, chamber, choroid, and 

 nerve, to be most indisputably organs of sight. The author referred 

 also to the binary origin of the nerve of the middle ocellus of the 

 vertex, as formerly pointed out by him in his paper on Pteronarcys ; 

 to the origin of ocelli in the same way as other dermal tubercles ; 

 and to the imperfect eye- spots in the Scorpionida being supplied 

 with nervous filaments from the same optic nerve which supplies the 

 recognised organs of vision in those animals. 



May 3. 



R. Brown, Esq., President, in the Chair. 



William Clarke, Esq., was elected a Fellow ; and Professor Von 

 Schlechtendal and Monsr. Louis Ren6 Tulasne, Foreign Members. 



Read the conclusion of a memoir " On the Vegetation of Buenos 

 Ayres and the neighbouring districts." By Charles James Fox Bun- 

 bury. Esq., F.R.S., F.L.S., &c. 



