ACIPENSER RUTHENFS. 



389 



supra-occipital shield has a long blunt triangular form ; the epiotic ossifications 

 are rather longer and quite as wide. The parietal ossifications terminate well 

 behind the eye, where the notch between them is occupied by the small divided 

 ethmoid. The margins of the squamosal scutes are parallel to those of the 

 parietal scutes, external to which they are placed. The frontal scutes are small, 

 the post-frontal is notched out above the eye, and there are no distinct pre-frontal 

 or nasal ossifications. The small ethmoid shields cover the rostrum to the extre- 

 mity of the snout, but they are so closely united together as to have the aspect 



Fig'. 178. ACIPENSEK KUTHENUS, SHOWING THE 



CllAMAL SCUTES ON THE UPPEK SIDE OF 

 THE HEAD. 



Fig. 179. ACIPENSEK RUTHENUS, SHOWING THE 



UNDEK SIDE OF THE HEAD, MOUTH, KAK- 

 BELS, POKES, ETC. 



of a single bone (Fig. 178). The cephalic mucus-canal subdivides in the usual 

 way, and opens by numerous pores which cover the under side of the rostrum, 

 except along the median line, in which there are three tubercles, two of which 

 lie in front of the barbels. The barbels are nearer to the mouth than to the 

 extremity of the snout ; their ends are fringed on the inner side (Fig. 179). 



The mouth is not exceptionally large, has the upper lip small, and only 

 slightly notched ; the lower lip is broader and always divided in the middle, 

 but both halves are in contact. The eyes are small, of equal size, nearly 

 round, and a little in advance of the position of the mouth. The diameter of 



