FISHES. 299 



The superior (No. 62)f consist of three pieces on each side, which 

 are attached under the internal extremity of the superior branches 

 of the three last arches. The three of the same side unite in ge- 

 neral in one plate, which forms with its fellow the vault of the 

 pharynx. 



The superior pharyngeal bones are adherent to the hase of the cra- 

 nium, and have but little mobility ; hut the inferior ones are raised or 

 depressed with inferior branches of the arches, and thus dilate or 

 narrow the entrance of the (Esophagus,, at the same time, that they 

 compress the food in its passaev. 



In the cyprins, the superior pharyngeal are small and toothless, a 

 large concave prominence of the Basilar furnished with a plate of 

 stony substance, fills up a part of the space which they usually occupy. 

 Sometimes, as in scarus, there is but one pair of them ; but we 

 see in general the branchial and pharyngeal apparatus containing 

 thirty-six osseous pieces, and if we counted those with which the 

 ai'ches are armed internally, this would amount to upwards of a 

 hundred. 



Vertebra. 



The vertebrae of fishes are known by the conical fossa, hollowed 

 (.ut of their bodies, upon the upper and lower surfaces. The double 

 hollow cones which thus always occupy the interval between two ver- 

 tebrae are filled up by a soft membranous and gelatinous substance, 

 which passes from one space to another, through a hole with which 

 each vertebrae is pierced almost always in its centre, so that these soft 

 bodies form a sort of gelatinous cord or chaplet upon which the verte- 

 brae are strung, and is alternately thin and bulky; it may even be 

 remarked here, that in certain species of chondropterygians, as the 

 lamprev, and partly in the sturgeon, the chimera, aud the polyodon ; 

 this hole of communication is so large, that the bodies of the verte- 

 brae may be considered as rings, and the cord which strings them 

 presents inequalities in its diameter, and resembles a true cord, which 

 name it has long borne in the lamprey. It is this circumstance that 

 gave rise to the observation that the lamprey had no vertebrae ; but it 

 is an easy matter to see their annular portions, and even the bodies of 

 the vertebra; may be detected with a little attention. 



The vertebrae in fishes, as in other animals (a) have at their upper 

 part, for the passage of the spinal marrow, an annular portion, from 

 the top of which most frequently a spinous apophyse arises (c, c, c\) 

 and in front andr ear of its Ball apoyhyses are found which 



correspond with the articular apophyses of other vertibrated animals, 

 but which in most cases merely touch or encroach slightly on each 

 other, without uniting by articular surfaces ; they nevertheless arc 



* The Pharyngeal of M. Geoffroy. 



f I have published the nature of the cord of the Lamprey, in vol. i. of the Mem. 

 du Museum. 



(«) In fig x. pi. iii. from 67 to 69, the different vertebrae are given by various 

 surfaces. 



