^{page 45 note *} I have demonstrated, in a brief notice, which, I believe, was inserted in some of the French journals, that it is by sight only that the vulture is led to discover his prey, and not by the sense of smelling.

^{page 49 note *} This is not present in the eye of the cassowary.

^{page 50 note *} See his Physiological Essays.

^{page 53 note *} See Plate III.Fig. I.

^{page 54 note *} The opinion that the annulus albus is muscular, has been often maintained, but, so far as I know, no proofs, derived from anatomy, of its muscularity, have ever been laid before the public.

^{page 55 note *} I observed a very singular fact in Africa, which first awakened my suspicions relative to the defective vision of the horse. In that country we were forced, from a deficiency of pasturage, to allow our horses to graze at perfect liberty on the open desarts, and they, so situated, seemed to acquire many of the habits which the animal would probably possess in a perfectly wild state. They grazed generally in small troops, to which an entire horse, or one of the boldest of the geldings, seemed to serve as protector; on the approach of strangers, the troop immediately collected into a circle, and remained so until the horse appointed to watch over the general safety had ascertained whether or not danger was to be apprehended, by a nearer approach of the object suspected. On one occasion, having gone into the fields with a few friends, of whom one was dressed in a morning gown, and, coming unexpectedly on the troop of horses, they were observed to collect immediately into a circle, and to detach one of their number, with a view to ascertain the nature of the very unusual appearance, which they evidently saw but indistinctly, though scarcely three quarters of a mile removed from the place we stood. It was now I remarked, with some surprise, that the horse did not, during the very long and circuitous course, approach much nearer to us, but made hastily for that situation in which we should be placed between him and the quarter from whence the wind blew; thus evidently employing the organ of smell in preference to that of sight.

^{page 58 note *} Some anatomists have confined their description of the uvea to the coating of the pigmentum nigrum, found on the posterior surface of the iris; but this is not generally received.

^{page 58 note †} These are described a little below.

^{page 59 note *} See Plate III.Fig. 2.

^{page 60 note *} Dr Portal, in one case, found hydatids situate between the choroid and retina. Unfortunately, he does not describe the pathology of the case with sufficient minuteness; the fact, however, is valuable.

^{page 61 note *} This may be considered as the hyaloid itself. Had I been aware at the time these dissections were performed, that an excellent continental anatomist (M. Ribes), had formed similar opinions regarding these internal ciliary processes, I should, perhaps, not have repeated my dissections so often as I did; but I was forcibly struck with the evident incorrectness of the descriptions given in some of the latest and best elementary works on the Anatomy of Man; and I was, moreover, anxious to disprove the idea lately adopted, that these folds or processes are fibrous or muscular bodies. M. Ribes' work has not yet reached this country; and I allude simply to a brief notice contained in an early number of the “Bulletin de Sc. Med.”

^{page 63 note *} i. e. Supposing an iris to exist betwixt the prolongation of the choroid and the reflected membrane of the cornea, which I do not believe to be the case.

^{page 65 note *} Plate III. Fig. 4.

^{page 66 note *} May not this membrane be the same with the dark coloured tunic, formed between the retina and vitreous humour, in the larger varieties of the cephalopodous mollusca?

^{page 66 note †} It has appeared to me, that, in many animals, and even in some of the ruminantia, the central artery of the retina does not send any branch through the centre of the vitreous humour.

^{page 67 note *} Some anatomists think that the optic nerve is merely distributed on the retina. There are several analogies in favour of this opinion, and even direct ocular inspection in the eyes of some fishes.

^{page 67 note †} The animal was said to have been sent to this country by his Excellency the Governor-General of Canada.

^{page 67 note ‡} It is probable, that, in all animals, the choroid passes directly over the entrance of the optic nerve; but it would be extremely difficult to demonstrate this, owing to the excessive tenuity and transparency of the membranous expansion.

^{page 68 note *} In the number of the Philosophical Transactions for 1810, (I quote from memory), four distinct muscles are described within the sclerotic, in the eye of the rhinoceros. The situation of these muscles corresponds exactly with the prolongation of the choroid membrane described in the text. I have examined the eye of the African or two-horned rhinoceros, but do not remember to have observed, any such muscles in it.

^{page 69 note *} I ought to have inserted, in this part of the observations, the result of my inquiries into the retina, its distribution, nature, &c.; but at the time this memoir was presented, I did not deem the researches sufficiently complete, or fitting to be submitted to the Royal Society of Edinburgh. But having repeated some of the dissections, and (the opportunity having presented itself) extended the researches, I made the important, and most unexpected discovery, that the foramen centrale of the retina, generally called the Foramen of Sœmmering, is not confined to the eye of Man, and of some Quadrumanous Animals, whose organisation somewhat approaches him, but is extended to the class Reptiles, contrary to the opinion of all comparative anatomists, The details of this very singular discovery are reserved for the Memoirs of the Wernerian Society, and the fact is simply announced in this place, to make my other observations more complete. “The foramen centrale of the retina exists in many lizards, as the superciliosa, scutata, striata, and Calotes, and is in them comparatively much more developed than in Man; but it is wanting in the lizards called gecko, mabuya” &c. See Memoirs of the Wernerian Society, Vol. v. Part 1.

^{page 71 note *} I have not been able to procure a copy of M. Maunoir's little treatise on the subject, so that I quote the passage from the “Traité D'Anatomie Descriptive,” by Dr Cloquet. Neither have I been able to obtain a sight of some observations which I find announced by the Journals, as having been made on the same subject by Dr Edwards of Paris. I regret this the more, because, from the known accuracy of that excellent physiologist, I feel well assured, that, on the points investigated by him, he would leave little to be done by future observers.

^{page 71 note †} Mr John Hunter, whose physiological opinions scarcely admit of question, seemed to think, a short time previous to his lamented death, that a fibrous structure was not the sine qua non of muscularity. The application of this to the textures of the iris and ciliary muscle is obvious.

^{page 74 note *} Were we to suppose, that, in the cat, owl, and parrot, the movements of the iris are dependent on volition, it would prove an unsurmountable objection to the doctrines which teach that the nerves of volition never pass through ganglia.