10 ( 



T1IK FKFSH-WATER FISHES OF EUKOl'K. 



than the frontal. The nasal and other shields lie in front of the remarkable 

 ethmoid ossifications. 



The eyes are rather large, round, equal in diameter, and entirely seen in a 

 view of the skull from above. The frontal interspace which separates them 

 measures five times the orbital diameter. The nares are large, rather distant, 

 and the lower uarine is nearly equal to the diameter of the eye. There is a 

 small row of pores on the anterior margin of the snout, over which numerous 

 small ossifications extend. 



The mouth lies immediately below the orbits in the middle of the under 

 side of the head, and its width is nearly equal to the width of the frontal 



Fig. 195. HEAD OF ACIPENSER HECKELII, 

 SEEN FROM AMOVE. 



Fig. 196. HEAD OF ACIPENSER HECKELII, SEEN 

 FHOM HELOW. 



interspace. The hinder lip is very imperfectly developed. The outer pair of 

 barbels is the longer, and when laid back reaches nearly to the mouth. The 

 barbels are near to the anterior end of the snout ; in the median line in front 

 of them is a slight ridge, and the under side of the head, both behind and in 

 front, is reticulated with large pores (Fig. 196). 



There are twelve slightly elevated dorsal shields, which have no conspicuous 

 spine, and are only slightly keeled. The first is broadest and flattest. At 

 first the shields are broader than long, but after the third the length and 



