150 



ACIPENSER. 



The mouth under the snout, without teeth, the jaws capable of 

 being drawn within the cavity. Barbs generally four, about midway 

 between the mouth and snout. Nostrils in front of the eyes; spiracles 

 behind the eyes; a single opening to the gills, covered with a 

 moveable operculum. The tail with unequal lobes, and the vertebrae 

 continued along the upper lobe as in Sharks. 



STURGEONS. 



With a general likeness to the form of the Sharks, there 

 are in this genus some remarkable departures from it, which 

 shew a greater variation from that type, and a nearer approach 

 to the bony class of fishes, than are seen in any other of the 

 plagiostdmes or cartilaginous tribes, in some particulars even 

 amounting to a positive contrast. We may conclude also that 

 the difference is equally great in the internal and less-observed 

 organization, especially of the brain, which is of small size, 

 and the nervous system in general; for their instinctive dis- 

 position of timidity and the absence of violent appetites are 

 more distinctly marks of variation, than the particulars to be 

 pointed out of their merely external shape. 



The head of the Sturgeons is lengthened into a snout, which 

 is slightly turned up; and the mouth is placed f ar beneath, 

 with sensitive tendrils about midway between the mouth and 

 snout. There is a spiracle behind each eye, by which 

 a current of water is supplied to the gills, when, as must 

 often happen from the manner in which they seek their food, 

 the necessary supply cannot be obtained through the mouth. 



But at this point the resemblance to the family of Sharks 

 becomes interrupted by the feebleness of the jaws, and the 

 entire want of teeth; and in place of a formidable arrangement 

 of offensive arms, as in that order, the lips are soft and fleshy, 

 with, in the case of the Common Sturgeon, separate lobes, 

 that from the nerves distributed to them we judge to be 



