VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 673 



with the lens, were by some believed capable of bringing it forwards; by 

 others they were supposed to contract, and by that action elongate the eye, 

 and remove the lens farther from the retina: but these processes could never 

 bring the lens forwards, unless the cornea was also moved forwards; for the lens 

 and processes forming a complete septum, the aqueous humour would prevent 

 the lens from making any advance in that direction: and the processes themselves 

 are neither strong enough in their muscular power, nor sufficiently attached to 

 the coats of the eye, to alter its form by their contraction. In birds likewise, 

 the bony rim renders this impossible. 



That the axis of vision is really lengthened, and the lens moved forwards, 

 for the purpose of adjusting the eye to see near objects, is rendered highly pro- 

 bable, since all the facts I have been able to collect seem to point out these 

 changes; nor can the action of the external muscles increase the curvature of 

 the cornea without producing them. If the axis of vision being lengthened was 

 believed, by some physiologists, to produce the whole adjustment of the eye to 

 see near objects; if the crystalline lens being moved forwards was supposed by 

 others to do the same thing; and if the cornea being rendered more convex 

 appeared at the first view equally to account for it; all the 3, when combined 

 for that purpose, must doubtless be considered as sufficient to produce the effect. 



Explanation of the figures. — Fig. 21, pi. 7, is a side view of the cornea of the eye of a goose, to 

 sliow tlie bony rim, and elastic annular ligament, in their natural situation ; a the bony rim ; b tlie 

 elastic ligament. 



Fig. 22, a view of the same parts, in the eye of the great homed owl, to show the difference of 

 structure; taken from a dried preparation in Mr. Hunter's collection.* 



Fig. 23, the marsupium in the eye of the turkey, attached to the bottom of the eye, and con- 

 nected by a transparent membranous union with the crystalline lens ; made visible by coagulation in 

 rectified spirits. 



Fig. 24-, the marsupium in the eye of the emeu, from New South Wales, with a portion of the 

 membrane that connects it to the lens ; the marsupium is drawn togetlier at that end next the lens, 

 giving it the appearance of a purse, from which it probably got the name marsupium. 



Fig. 25 and 26, two views of the crystalline lens of the eye of a goose, to show tlie attachment of 

 the marsupium to the lens. 



These different drawings are of the natural size of the parts they represent. 



//. Some Particulars in the Anatomy of a JVhale. By Mr. John Abernethy. p. 27. 



There are some particulars in the anatomy of the whale, which I believe have 



either entirely escaped observation, or have not been as yet communicated to the 



• Since this lecture was read before the r. s.. Sir Joseph Banks has put into my hands a paper on 

 the anatomical structure of the eye, in whicli there is a plate, containing 4 views of the bony rim in 

 the owl's eye. The parts they represent are exactly similar to those shown in the 22d figure ; and had 

 the paper been published in this country, would have rendered it unnecessary. The paper is inti- 

 tuled Esposizione Anatomica delle parti relative all'Encefalo degli Uccelli, del Sig. Vincenzo iVIala- 

 carne ; it is published in the Italian Transactions, called Memorie di Matimatica e Fisica della Society 

 Italiana, Tomo 7. Verona, 179+ . — Orig. 



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