394 



THE FlIF.STT-WATEl; FISIIKS oF EFKolM-:. 



covered by bony shields^ wbieli ave eloiiiratod in iho direction of Ihe head 

 length, liave elevated centres, and are marked by radiating" ril)>. The lirst 

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

 shaped supi-a-oceipital shield, which is contained between the hinder ends of the 

 parietal shields. Neitlier the supra-occipital, parietal, nor first dorsal scutes touch 

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

 The sfpiaraosal, parietal, and supra-occipital plates all terminate in tlie same 



Tip;. 184. — ACU'ENSEii stei.latus, 



HEAD SEEN I'KOM AliOVE. 



— ACirENSEK STKEI.ATX'; 

 ^EEX FROM liHNEATll. 



transverse line. The parietal shields are long, and extend f(n-ward to the anterior 

 third of the orbit. The frontal shields arc in tlie usual position, with tlic pos(- 

 f rental behind the eye, and the pro-frontal in contact with it, iu front of the 

 eve, so as to exclude the frontal scute from the orbital border. Tliere 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 pre-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. Ou 

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



