322 Anatomical Discoveries respecting [M^y, 



wise in the silurus glanis and cobitis fossilis and the barba- 

 tula, is accompHshed by means of six ossicula auditoria (thi;ee 

 of which are phiced on the right side and three on the left) 

 united with the three superior vertebne by articulation. These 

 may be compared to the stapes, incas, and malleus. The apex 

 of the malleus always adheres to the upper part of the swimming 

 bladder. 



4. All the fishes just enumerated are furnished with two 

 cavities (atria) situated in the first vertebra near the foraraei;i 

 occipitale. Each cavity is shut by the stapes of that side in 

 which it is placed ; and the stapes may either be drawn from it, 

 or a])plied to it, by the action of the swimming bladder. Hence 

 this cavity may be compared to the fenestra ovalis in man. 

 Each cavity {atrium) is furnished with a little bone peculiar to 

 itself which shuts it up. 



5. In all the fishes above enumerated, each cavity {atnum) 

 has access to the sinus imparis by means of two holes cut in the 

 occipital bone. This sinus is situated in the middle part of the 

 basilary portion of the occiput. Passing into the cranium like 

 a fork, it is divided into two canals, of which the right passes to, 

 the right labyrinth, and the left into the left labyrinth, to which 

 it adheres in that place in which the saccus and vestibulura 

 membranaceum are united. 



6. In all the fishes above enumerated, there are found certain 

 ostia leading into the same cavity of the cranium, covered with 

 •s'kia and muscles, which must be considered as the fenestr-ce of 



the osseous vestibulum, since the cranium of osseous fishes 

 serves the same purpose as the vestibulum osseum. 



7- In all these fishes, the three superior vertebrx receiving, 

 the ossicula auditoria are increased, augmented in size, and 

 remarkably altered. 



8. All these fishes possess an interior lapillus of the sack, re- 

 markable by a peculiar form, long, and spinous. 



9. The ossicula auditoria of the cyprinus are enclosed by two 

 membranous auditorial fossae, one of which is situated on the 



^ight side, and the other on the left side of the three superior 

 v^fertebroe. The fossae auditorial communicate with the cavity of 

 the cranium by the two lateral occipital bones, and contain an 

 oily liquor of the same nature as that in the cranium. 



10. The ossicula auditoria of the cobitis fossilis are included 

 in a cavity of the transverse process of the second vertebra, 

 answering the purpose of the cavity of the tympanum. 



1 1 . The osseous capsule, enclosing the swimming bladder of 

 the cobitis fossilis is formed from the transverse ]irocesses of the 

 third vertebra, expanded into an osseous bulla. This capsule haa 

 two great external apertures, surrounded outwardly by an 

 elevated margin, covered by the external cutis. By two other 

 anterior openings, the apex of the. malleus of the right and left 

 side enters into the osseous capsule, and is there fixed to the 



