394 



THE FRESH-WATER FIHIIES OF EUROPE. 



covered by bony shields, which are elongated in the direction of the head 

 length, have elevated centres, and are marked by radiating- ribs. The first 

 dorsal shield is triangular, and its anterior point only touches the small wedge- 

 shaped supra-occipital shield, which is contained between the hinder ends of the 

 parietal shields. Neither the supra-occipital, parietal, nor first dorsal scutes touch 

 the epiotic shield, which is in contact with the hinder margin of the squamosal. 

 The squamosal, parietal, and supra-occipital plates all terminate in the same 



Fig. 184. ACIPENSER. STELLATUS, 



HEAD SEEN FROM ABOVE. 



Fig'. 185. ACIl'ENSEK STELLATfS, 

 HEAD SEEN FROM UENEATH. 



transverse line. The parietal shields are long, and extend forward to the anterior 

 third of the orbit. The frontal shields are in the usual position, with the post- 

 frontal behind the eye, and the prc-frontal in contact with it, in front of the 

 eye, so as to exclude the frontal scute from the orbital border. There is a 

 broad and deep furrow or depression on the head between the parietal and 

 frontal plates (Fig. 184). 



The nares consist of two large contiguous apertures adjacent to the eye 

 and immediately in front of the p re- frontal scute. The rostrum, or snout, is 

 covered with a number of elongated plates, some of which are partly marked 

 with radiating grooves, between which pores open from the cephalic canal. On 

 the under side of the snout there is a long, raised, smooth area, the hinder 



