8. HOLOCENTKUM. 37 



interspace between the eyes ; there is no distinct cavity between 

 them, nor on any other part of the skull, except the groove for the 

 posterior processes of the intermaxillaries ; this groove is narrow, 

 elongate, nearly equally broad anteriorly and posteriorly, and extends 

 between the principal frontals to the level of the anterior fourth of 

 the orbit. These bony ridges radiate behind in ten or more 

 branches, fan-like arranged; the hinder part of the upper roof of 

 the orbit is covered with spines, dii'ected backwards. 



The nuuvillary bone is stylitbnn in its inner half, then gradually 

 widens into a moderately broad plate, with a straight anterior edge, 

 and the posterior rather concave ; the supplementaiy bone is very 

 narrow, tapering above. The intermaxillaries are separated from 

 one another by a small notch ; they are nearly as long as the max- 

 illaries, and have a shght prominence behind. The mandibulaiy^ 

 without protuberance in front. 



The dentition is formed by villiform bands only, without any 

 canines or granular prominences. The bands on the jaws reach to 

 the extremity of the bones ; the vomerine teeth are arranged in two 

 narrow bands, meeting under an obtuse angle ; the palatine teeth 

 form a narrow band extending on the pterygoid. The teeth of the 

 pharyngobranchials are placed in several round patches, one of which 

 is larger and ovate. 



The infraorbital arch is rather narrow, and nearly equally broad, 

 the pra^orbital being not much -svidcned ; its ossification is complete, 

 and there is no outer membrane. The lower edge only is serrated ; 

 the pra3orbital strongly armed M'ith spinous teeth, directed backwards ; 

 the anterior and posterior ones are strongest. The turbinal bone ' 

 overreaches the intermaxillary with a short point. The infi'aorbital 

 arch has inside a broad concave plate, forming nearly a half-circle, 

 and supporting the eye -ball, together with the entopterygoid, which 

 is very broad, and attached to the basisphenoid by a narrow liga- 

 ment only. 



All the o^jercles are distinctly serrated and striated as far as they 

 are not covered by scales. The opercvdum is one and a half as high 

 as wide (the spine included) ; on its tipper third it has two flat 

 ridges, divergent and terminating in two flat spines, the upper of 

 which is long and strong ; the serrature is rather coarse, and formed 

 by small spinous teeth, the terminations of the striae. The sub- 

 operculum is elongate, crescent-shaped, its denticulations scarcer and 

 coarser than those of the operculum ; the edge before the pectoral is 

 entire. The interoperculum has posteriorly a notch at the place 

 where the prasopcrcular spine passes ; the denticulations are very 

 coarse and directed backwards. The pra^operculum has a simple 

 ridge only, with regular serrature on both the edges ; they meet 

 nearly at a right angle. The prajopercular spine runs in the same 

 line with the loA^'er edge, and its length is 2i in that of the posterior 

 edge. 



The vestibular opening is elongate or irregularly ovate : I could 

 not find any bony plate in connexion with the tympanum, as is found 

 in Myrl^^ristis a'h'Stjis. 



