408 



THE FRESH- WATER FISHES OF 



tapering 1 in front, and convex behind, receiving a slight tooth from the first 

 dorsal shield in the middle of the posterior border. The epiotic shields arc- 

 longer than wide; the sqnamosals do not extend as far backward as the parietals, 

 and their centres are slightly anterior to those of the latter, while the centres 

 of the epiotics and supra-occipital are in a transverse line. The frontal shields 

 are large and extend a little farther back than the post-frontal scutes. The 

 pre-frontal shields are strongly developed, and form the anterior borders of the 

 orbits. The nasal shields are anterior to the frontal. The eyes are partly 



Fig. 197. HEAD OF Afll'ENSEK NASUS, 



SEEN FROM ABOVE. 



Fig. 198. HEAD OF ACIPENSEH NAM S, 

 SEEN FROM BELOW. 



covered by the pre-frontal and post-frontal plates. A median longitudinal 

 depression extends along the head between the frontal and parietal shields. 



The under side of the head shows the mouth, as usual, in the middle of the 

 head-length ; it is nearly as wide as the frontal interspace between the orbits. 

 The middle portion of the lower lip is not developed. A strong elevated 

 median ridge extends from the extremity of the snout backward to the upper 

 lip, widening somewhat behind. The barbels are rather in front of the middle 

 distance, between the mouth and the end of the snout. The outer pair is 

 the longer ; they reach back to the upper lip (Fig. ] ( JS). 



There are thirteen well-developed shields on the back. They are broader 



