2. AULOSTOMA. 537 



opercle. Four slender branchiostegals. Tlie gill-opeuing extends 

 to below the eye, the gill-membranes being attached to the front 

 end of the iirohyal ; the glossohyal is very long and slender. Four 

 gills, with a narrow slit behind the fourth; pseudobranchifv well 

 developed. 



A long narrow bony shield, half as long as the snout, is joined to 

 the occiput and extends along the neck. The body is compressed, 

 highest between the origin of the dorsal and anal fins, whilst the tail 

 behind these fins is veiy low ; its greatest depth is one-fifth of the 

 length of the head, and the least depth of the tail is only one-third 

 of the depth between the vertical fins. It is covered with small 

 ctenoid scales, which have the free margin strongly ciliated ; there 

 are about thirty-five in a vertical line below the anterior dorsal 

 spines. 



The pectoral fins have a broad, slightly oblique base and arc 

 rounded ; they are shorter than the part of the head behind the orbit. 

 The ventrals are one-third nearer to the anal than to the base of the 

 pectoral ; they are shorter than the pectorals, and have the rays of 

 nearly equal length, the outer ray being simple, but articulated. 

 The spinous dorsal fin is generally composed of nine or ten slender 

 spines ; they are feeble, about as long as the orbit, and remote from 

 one another ; each has a broad niembranc behind, and can be received 

 in a slight groove ; if laid backwards they scarcely touch one an- 

 other. The soft dorsal and the anal are opposite to each other ; thn 

 length of the base of the former is nearly equal to its distance from 

 the caudal, and a little less than the length of the base of the anal ; 

 the anterior rays are short ; the fourth is the longest, forming the 

 highest part of the fin : the anal is similar in shape to the dorsal. 

 Caudal rhombic, TN-ith the two middle rays longest. 



Ground-colour brownish -olive (in spirits), with one or two series 

 of brown (blue) dots along each side of the back ; another rather 

 irregular series of round brown spots from the pra^opcrculum along 

 each side of the belly to the anal fin. Three or four silvery lines 

 along each side of the abdomen, intcrnipted on the head, where they 

 are replaced by irregodar oblique streaks ; a brown streak along the 

 posterior margin of the maxillary ; each nostril with a brown spot. 

 The seven anterior dorsal and anal rays are crossed by a black streak 

 parallel to, and rather remote from, the base of the fins ; caudal fin 

 with two round black spots, one above the other, the lower being 

 sometimes absent. 



The stomach is spacious, elongate, with thin membranes, which 

 become thicker towards the pjdorus ; it passes without curvatiu'e or 

 dilatation into the intestine, which is extremely short, quite straight, 

 without curve or circumvolution, and rather wider at its commence- 

 ment than posteriorly ; two pyloric appendages of moderate size 

 on each side of the pyloric portion of the stomach. Aii'-bladder 

 large. 



From the shortness and simple structiu'C of the intestinal tract, the 

 inference might have been di-awn that this fish is carnivorous ; and 

 the stomach, indeed, contained the remains of small fish. 



