25 



composing which, however, are still less developed than those of that 

 part of the membrane which lies over the tapetum, in the eyes of the 

 horse, ox, &c. They are in fact not hexagonal, but circular, a struc- 

 ture similar to which the author has found in the eye of a very 

 young human foetus. 



Behind and around the ciliary processes, and on the posterior sur- 

 face of the iris, the membrane of the pigment ceases to present the 

 hexagonal structure, although still composed of small irregularly 

 rounded masses of about the same size as the hexagonal plates, to 

 which they are evidently analogous. 



This change in the structure of the membrane of the pigment, 

 which is only partial in the eyes of the Mammiferro, the author has 

 found to obtain in its whole extent, in the eyes of those animals 

 lower in the zoological scale which ho has examined, except in the 

 eye of the Cuttlefish, in which there is an approach to the hexagonal 

 structure in that part of the pigment which lies on the posterior sur- 

 face of the part in which the crystalline lens is fixed. 



May 6. 



Sir THOMAS MAKDOUGALL BRISBANE, 

 President, in the Chair. 



The following Donations were presented : — 



Geological Sketch of the Vicinity of Hastings. By W. H. Fitton, 



M.D., &c. — From the Author. 

 Notes on the Progress of Geology in England. By W. H. Fitton, 



M.D. — From the Author. 

 Abstracts of the Papers printed in the Philosophical Transactions of 



the Royal Society of London, from 1800 to 1830 inclusive. 2 vols. 

 Proceedings of the Royal Society of London, No. 11. 

 List of the Fellows of the lloyal Society of London for 1832-33. 

 Addresses delivered at the Anniversary Meetings of the Royal 



Society of London on November 30. 1831, and November 30. 



1832. — From the Boyal Society of London. 

 Memoirs of the Royal Astronomical Society. Vol. V. — From the 



Society. 

 Astronomische Nachrichten. No. CCXXXIII. to CCXXXVIII.— 



From M. Schumacher. 



