OP NEW SOUTH WALES. 167 



The humerus is large and of somewhat triangular shape, the 

 posterior angle extending to the upper part of the origin of the 

 pectoral fin, while beneath on the anterior portion there is a 

 a broad notch to receive the upper part of the coracoid bone. 

 This bone is nearly square, with an oblique groove in the middle. 



The dorsal cuirass extends on the back from the head, to 

 which it is firmly fixed, the suture being rigid and dovetailed, in 

 one apparent piece (*) to about one-fifth the entire length of the 

 fish beyond the tail ; it becomes gradually smaller towards the 

 extremity, and has articulated to its apex, running in the same 

 direction a spine of about half an inch in length, to which I give 

 the name of the first dorsal spine. 



The whole of this part of the cuirass is longitudinally striate, 

 and for the most part punctate. The lateral portion of the 

 cuirass seems to consist of four plates, closely adherent to the 

 dorsal part just mentioned, (the suture being scarcely visible) and 

 extending downwards along the middle of the body as far as the 

 middle of the sides. The first plate is narrow from its contact 

 with the head and operculum, until past the humerus and 

 pectoral fin, where it expands downwards to the middle of the 

 body ; the second plate is shorter than the first, rather longer 

 than deep, and quite rectangular ; the third is about the same 

 length as the second, but becomes less deep towards the fourth ; 

 this last runs out entirely into the dorsal portion above the tail. 

 The lateral sutures of these plates are deeply serrated, the serra- 

 tions dovetailing in the most perfect way. These lateral plates, 

 or at least three of them, have a fan-shaped series of fine striae, 

 expanding downwards from a nucleus near the dorsal suture. 

 The body below these lateral plates is covered with a perfectly 

 transparent membrane, through which ten pairs of ribs are 

 visible, and terminates beneath in a very trenchant edge which 

 extends from the snout to the vent. 



The pectoral fins are of moderate size, situated much nearer 

 to the ventral fin than to the eyes, and consist of eleven rays of 

 nearly uniform length. The ventral fin, for there is only one, is 



* Dr. Gunther, in his description of A . scutata, speaks of this part as consisting of 

 five bones. 



