DR. RICHARDSON'S DESCRIPTION OF AUSTRALIAN FISH. 85 



At its angle there are two spinous points, with a narrow rounded notch between them, 

 and beneath them the interoperculum is firmly joined to the base of the preoperculum. 

 The operculum is small and triangular, with a short flattish spine at its posterior corner, 

 and its upper edge is divided from the hinder one by a projecting, angular, but not 

 spinous point. A stiff membranous flap underlies the bony operculum, and its most 

 posterior part is a rounded lobe, situated above and behind the upper angular point of 

 the bone. The supra-scapular soldered to the occiput projects backwards to beyond the 

 third dorsal spine, having acutely serrated edges and a sharp spinous point. The 

 scapula has a nearly semicircular form, with a central ridge, which is prolonged into an 

 acute spine of the same size with the preorbitar one. 



The gape of the mouth extends backwards as far as the anterior nostrils. The thin 

 lips, gill-membranes, and a considerable space round the pectoral and ventral fins, and 

 forwards to the sjonphysis of the lower jaw, are clothed with smooth white skin. The 

 limbs of the lower jaw are granulated, though not so coarsely as the rest of the head, 

 and the granulations are more distinctly porous. The teeth on the intermaxillaries are 

 short, close, and villiform. There is a small dental surface on the chevron of the 

 vomer, not very perceptible to the eye, and also two pairs of patches of densely crowded 

 villiform teeth on the upper pharyngeal bones, and one pair on the inferior bones. The 

 rakers of the exterior row on the outer branchial arch are short, spatula-shaped, and 

 studded on the tips with minute teeth. All the other rakers are still shorter. The 

 tongue is smooth. 



The body is covered with rather large scales, which are irregularly oval, and often 

 oblique. The basal half of each scale is impressed by five or six undulations or furrows, 

 producing corresponding crenatures on the margin, and the uncovered surface and 

 margin are studded with minute spiny points. There are about twenty-one rows of 

 scales in a vertical line on the fore part of the body ; four above the lateral line, and 

 sixteen below it. The lateral line runs near the back, and forms an acute and not much 

 elevated spiny ridge, which forks when it meets the caudal fin, and is lost on its surface ; 

 it is composed of seventy-five scales up to its bifurcation. These scales do not exceed 

 those of the body in size, but have a widely different form, being tubular, both longi- 

 tudinally and transversely, and in fact bearing no very distant resemblance to the heads 

 of some species of Zygana;. The uncovered part of the scale is armed on the surface 

 and margin with strong spines, which also appear to be hollow. The spines become 

 fewer the nearer the scales are to the tail. 



The dilated ends of the dorsal interspinous bones form twenty-seven plates, which be- 

 stride the back like so many saddles with the hollow side turned upwards, each flap or 

 wing tenninating in an acute triangular spine directed backwards, and forming, with its 

 fellows, a serrated margin to the dorsal furrow on each side of both dorsal fins. These 

 plates are successively narrower as they are more posterior, and two or three of the 

 foremost ones have more than one spinous point. 



