and the Anatomy of Fishes* 293 



but *' ossicula near the anterior cervical vertebrae ;" then — " on 

 the vestibulum are neatly-formed stones," &c. From this, it 

 would seem as if there were two different sets of ossicula 

 belonging to the organ of hearing. 



I should scarcely conceive that the remarks just cited from 

 Blumenbach bore any allusion to the bones found upon the 

 brain of the Guiana fishes. 



Cuvier's delineations and descriptions differ much from what 

 I have observed in the fishes of Guiana, both in respect to the 

 inclosure and situation of those ossicula; yet, as affording 

 points of resemblance, they serve, perhaps, to identify those 

 encephalic bones with the ossicula auditus as they are called, 

 which, in the northern or European fishes, it seems, are 

 placed in a lateral cavity, or rather a lateral extension of the 

 cerebral cavity, much exceeding the volume of the brain, and 

 containing the labyrinth, &c. ** Get appareil entier (the semi- 

 circular canals, &c., in fishes) est situe dans les cot^s de la 

 cavite du crane, et s'y trouve fixe par du tissu cellulaire, des 

 vaisseaux et des brides osseuses ou cartillagineuses *." 



It appears that in the fishes of the North these ossicula vary 

 in different species from one to two or three in number (i. e. 

 on each side), and are enveloped in the sac of the labyrinth 

 along with the common pulp, ui rij;*! 



In the fishes of Guiana, the brain of which I have examined, 

 I have found but two of these petrous bones, each separately 

 inclosed in its proper tunic, which is exceedingly thin and pel- 

 lucid. Being suspended by slender cords attached to the sac, 

 they seem in a manner to float, in a gelatinous liquor, in the 

 cranial cavity, in contact with the brain — not as in the cod 

 and others, in which the sac is attached, with some degree of 

 firmness, to the base and sides of the cranium. 



If these ossicula are, in the fishes of Guiana, fewer in num- 

 ber, they are more developed or larger than in the northern 

 fishes. One of these bones, in a gilbagre of three feet in 

 length, weighs upwards of seventy grains, whilst in a full- 

 grown cod (of the same size) it does not exceed twenty grains. 

 Yet M. Cuvier observes, they are larger in proportion in the 

 cod than in any other fishes (1. c, p. 458.) 



" * I'i .<*«' Cuvier, Anat. Comp., tome ii., p. 455. 



