324 PHILOSOPHICAL TRANSACTIONS. [ANNO 1782. 



cornea of the monoculus may be divided into layers, the number of which however 

 he could not asceitain; but he once met with a cornea in which the internal layer 

 and its cones were separated from the external lamina and their cones. A portion 

 of the internal layer is shown fig. 1 1 ; and the cones, very much magnified, with 

 their septa or partitions, are exhibited fig. 12. 



It is very well known, that all crustaceo'as animals cast their shells once a year, 

 and are left witli a soft, tender covering, which, after some time, acquires the 

 hardness of the former shell. As the cornea in these animals is a part of the 

 shell, it is reasonable to suppose, that the internal layer is left with the soft 

 covering, containing the rudiments of the future cornea; and this is the more 

 probable, from Mr. A. having met with an eye where the internal layer was 

 separated from the more external ones : see tig. 1 1 . 



The structure of the small eyes being less elaborate than that of the large 

 ones, their internal appearance, when placed in a microscope, will be described 

 in a few words. They consist of an oval, transparent, horny plate, of an amber 

 colour, in the centre of which stands a single cone, through which and the oval 

 plate the light passes : see fig. 10. These small eyes are analogous to those small 

 eyes of other insects which entomologists have called stemmata. The lenticular 

 structure of the corneae of insects in general certainly assists in condensing or 

 strengthening the light, in its passage to the immediate organ of sight. It is 

 probable, that the cones in the monoculus have the same effect. Whether they 

 answer that purpose, in a more or less perfect manner than the lenses in the 

 generality of insects, is what Mr. A. cannot determine. 



Explanation of the figures. — Fig. 8, pi. 5, the monoculus polyphemus. a a The large eyes, bb 

 the small ones. Fig. 9, one of the large eyes magnified. Fig. 10, One of the small eyes magnified. 

 Fig. 11, a portion of the internal layer magnified. Fig. 12, the cones magnified with their septa or 

 partitions. 



END OF THE SEVENTY-SECOND VOLUME OF THE ORIGINAL. 



7. On the Name of the New Planet, in an Extract of a Letter from William 



Herschel, Esq., F. R. H. Fbl.73, Anno 1783. p. 1 . 



By the observations of the most eminent astronomers in Europe it appears, 



that the new star, which I had the honour of pointing out to them in March, 



1781, is a primary planet of our solar system.* A body so nearly related to us 



* The observations on this new planet, at first suspecled to be a comet, are abridged at p. 154, 

 of this volume. Dr. Herschel, the discoverer, here calls it the Gcrgiuni Sidus, or Georgian planet, 

 in honour of his Majesty; by which name it is commonly distinguished in this country, lint, in 

 other countries it is often called by other names : as Ouranus, Uranius, Herschel, &c. Its astrono- 

 mical mark or character is ]$. By later observations and calculations it has been determined, that 



