236 



the fins that their relative length and height in the females are 

 about the same as they are in the young ones and young 

 specimens, but in the males they are considerably larger; this 

 is especially the case with regard to the height of the 2"'* 

 dorsal fin. 



The difference of sex is also shown by the rays of 2°'' 

 dorsal fin projecting with naked points a good deal beyond the 

 membrane of the fin in the male specimens ; the same is also 

 the case though to a less degree with the upper rays of the 

 pectoral fins ; but such is not the case in the females. More- 

 over it shows itself in the greater supply of dermal spines 

 in the fins of the males than in the females. In the males 

 3 — 8 of the upper rays of the pectoral fins on the inner-side, 

 8 — 11 on the outer side are more or less rough to the touch, 

 in the females only relatively 2 — 4 and 5 — 7 ; in the females 

 only the upper rays of the caudal fin are more or less rough, 

 in the males on the contrary, the lower ones are also often 

 rough; almost all the rays of 2°'^ dorsal fin are rough (with the 

 exception of the posterior ones of young specimens) yet the 

 roughness generally extends farther in the males than in the 

 females. In the young ones the rays are smooth or only show 

 an intimation of roughness. 



In the young ones (68 — 122 mm. long) the horns on front 

 and occiput are very small, low and smooth. In larger speci- 

 mens there is a great individual variation. In one female of 

 of 234 mm. they are comparatively not much larger than in the 

 young ones, at any rate not the posterior ones, and their sur- 

 face is smooth, covered by the skin, only, at the distal end of 

 the ones farthest back we can, by the aid of a pocket lens, 

 see some small asperities projecting. In one female of 219 mm. 

 they are considerably larger, the front ones almost smooth, the 

 posterior ones on the contrary spiny along the upper margin ; 

 and finally in one female of only 181 mm. they are compara- 

 tively still larger, especially the anterior ones, and both pair 



