ACIPENSER STURIO. 



411 



occipital. Their centres are nearly in a line with that of the supra-occipital. 

 The squamosal shields are small, smaller than the epiotic, and their centres are 

 in a transverse line with those of the long parietals. 



The parietal shields are more in contact than usual, the narrow ethmoid 

 ossification in front only penetrating slightly between them, while it assists 

 (with small anterior ethmoid ossifications) in dividing from each other the long 

 and large frontal scutes which are only a little shorter than the parietal scutes. 

 The post-frontal scute is narrow, and extends behind and over the orbit for the 



Fig. 200. HEAD OFACIPENSER STUUIO, 

 SEEN FROM ABOVE. 



Fig. 201. HEAD OF ACIFENSER STURIO, 

 SEEN FROM BELOW. 



eye. It unites with the pie-frontal scute in front. The snout is covered with 

 a number of closely packed elongated ossifications, which, however, leave a 

 naked margin, which shows pores. The operculum is large, flat, and granular. 

 The eyes are rather large, ovate, equal, and look laterally, and the breadth of 

 the frontal interspace is less than four times the diameter of the eye. The 

 nares are somewhat in advance of the eye, and the lower narine is longer, and 

 not so large as the upper rounder one. On the under side of the head the 

 mouth is a little nearer to the gill-aperture than to the snout ; it is placed, 

 as usual, between the eyes, but its breadth is less than the frontal interspace. 

 The lip is expanded into two large pads on the lower jaw, but they are 



