H^MULON ARCUATUM. - 125 



margin of the orbit, whence it is smooth to the snout. The gill-openings are 

 large ; there are seven branchial rays, of which the three last are delicate. The 

 supra-scapular is rather small, semicircular behind, and strongly serrated. 



There is a single dorsal fin, large, emarginate, and beginning with the pectoral, 

 just behind the gill-openings ; it has in its anterior half twelve spines, the first 

 very short, the fourth, fifth, and sixth longest ; they are all more or less com- 

 pressed, and partially received in a groove ; the posterior half has one spine, and 

 seventeen soft rays, covered with large scales at their roots, and minute scales to 

 near their tips. The pectoral is rather broad and short, though it extends farther 

 back than the ventral ; it has sixteen rays, and a slight scaly fold in the axilla 

 above. The ventral is large, broad, and terminates in front of the vent ; it has one 

 spinous and five soft rays, with a large triangular fold in the axilla. The anal is 

 large, broad, and has three spines, the first minute, the second of great size, and 

 the third as long as the second, though not half as stout ; there are nine soft 

 rays, the first and second longest ; the spines are partially received in a groove, 

 and the soft portion is covered with scales, like the dorsal. The caudal is large, 

 strong, forked, and has twenty rays, covered with large scales at their roots, and 

 with smaller scales to near their tips. 



The scales are large, finely ciliated behind ; there are fifteen in the vertical 

 direction, and fifty in the longitudinal. The lateral line corresponds with the 

 margin of the back to the posterior extremity of the dorsal fin, when it descends 

 to the median plane, and thus continues, and is marked by two or three radiating 

 striae on each scale. 



Dimensions. The head is one third the length of the entire animal ; the 

 greatest elevation without the dorsal fin is one head ; total length, ten inches. 



Colour. The head is dusky above, but the sides are marked with horizontal 

 lines of ultramarine blue ; there is a red blotch at the angle of the mouth, which 

 extends along the lower lip for some distance ; the body is olive-brown above, and 



