74 DR. RICHARDSON'S DESCRIPTION OF AUSTRALIAN FISH. 



Form oval, the curve of the back from the snout to the end of the dorsal being elHp- 

 tical, and rather more regular than that of the belly, which is flattened in at the ven- 

 trals. The greatest depth of the body is midway between the ventrals and anal, and is 

 equal to half the length from the snout to the end of the dorsal, or to one-third of the 

 whole length, measured to the tips of the caudal lobes. The height of the naked part 

 of the tail is equal to one-third of that of the body, and its thickness to one half of its 

 own height. The body is thickest on a line with the pectoral fins, which are attached 

 low down ; and its transverse measurement is considerably less than half the height. 

 The belly is full and rounded : the back thins off with less lateral convexity, and is 

 somewhat acute on the ridge. 



The head appears short, because of the great descent of the arched profile beneath the 

 summit of the dorsal curve ; but it measures to the tip of the gill-cover nearly one-third 

 of the length of the fish, excluding the caudal fin. The end of the snout is on a line 

 with the tip of the gill-cover, and when the mouth is closed the lower jaw inclines up- 

 wards to within thirty degrees of being vertical. The top of the head is very convex 

 transversely ; the distance between the eyes is equal to a diameter and a half of the 

 orbit ; the breadth of the snout to one diameter ; and posteriorly the head and nape thins 

 off, so that the breadth between the supra-scapulars is less than between the eyes. 



The eye small, and exactly round, is situated about half its diameter beneath the pro- 

 file of the forehead, six times as far above the isthmus of the gill-membranes, one dia- 

 meter behind the mouth, and two anterior to the gill-opening. It is surrounded by a 

 scaleless bony circle, which is lined by a narrow, thick, smooth, immoveable membra- 

 nous edging or ej^elid, whose inferior half is finely crenated. The broadest part of the 

 circle is formed by the anterior infra-orbitar, whose margin is curved and slightly undu- 

 lated, but not serrated. The posterior infra-orbitars are much narrower, and the orbitar 

 margin of the frontal narrower still. All are pitted or furrowed, and the infra-orbitars 

 are perforated by many pores. The nostrils, situated in a smooth stripe of skin near 

 the anterior angle of the eye, are small, and the anterior opening has a slightly raised 

 tubular margin. 



The mouth is rather small, its commissure not reaching backwards beyond the nostrils. 

 When it is extended, the lower jaw is depressed below the horizontal line ; the inter- 

 maxOlaries are slightly protruded, and the orifice thrown forwards. The labial is broad 

 and truncated below, having a triangular form ; its articulation alone glides under the 

 infra-orbitar, its wide lower extremity passing beyond the tip of the intermaxillary, so as 

 to overlie the limb of the lower jaw when the mouth is shut, and touch the circum- 

 ference of the orifice when it is open. 



Teeth. — Most of the dental surface on the intermaxillaries and lower jaw is armed 

 with villiform teeth ' ; but the inner rows at the symphyses, and also on the limbs of the 



' I use the term recently introduced by Mr. Owen to express the French "en velours." 



