390 



BULLETIN OF THE BUREAU OF FISHERIES 



Zenithicus spawns in November and nigripinnis spawns in late December and 

 early January, so that the state of ripeness of the sex products may aid also in sepa- 

 rating certain specimens. 



Zenithicus differs from Jciyi chiefly in the length of the mandible and paired 

 fins, size of the eye, and body shape. In zenithicus the mandible is heavy, never 

 with a symphysial knob, and usually shorter than the upper jaw; in Iciyi the mandible 

 is frail, usually with a symphysial knob, and equals or exceeds in length the upper 

 jaw. 



Zenithicus has a smaller eye and much shorter paired fins than Jciyi and, more- 

 over, attains greater size. Extreme examples of the former measure 312 millimeters; 

 of the latter, 245 millimeters. The eye, of course, changes in proportion to the 

 head with growth, and while the specimens of zenithicus average larger than the 

 kiyis, they were all taken in the same nets, and the differences thus are those that 

 would be exhibited by specimens in the same catch. The figures are given: 



H/E: 



zenithicus, (4) 4.2-4.5 (5), with 93 per cent more than 4.1. 

 kiyi, (3.6) 3.8-4.2 (4.3), with 19 per cent more than 4.1. 

 Pv/P: 



zenithicus, (1.7) 2-2.2 (2.6), with 97 per cent more than 1.7. 

 kiyi, (1.1) 1.4-1.7 (2.1), with 18 per cent more than 1.7. 

 Av/V: 



zenithicus, (1.2) 1.4-1.6 (2), with 90 per cent more than 1.3. 

 kiyi, (0.96) 1-1.3 (1.4), with 2 per cent more than 1.3. 



The body of zenithicus is much wider and less deep, and the slope of the body 

 contours as seen from the side is more gradual than in Jciyi. The shape of the head, 

 seen from the side, is also different because of the difference in position of the pre- 

 maxillaries in the two forms. Zenithicus shows, on the average, less pigment on 

 the head, back, and fins. Female Jciyi will show ova in a more advanced state of 

 development than females of zenithicus taken at the same time, as Jciyi probably 

 spawns a month earlier. 



Zenithicus may be distinguished readily from hoyi by its shorter and heavier 

 mandible and shallower and more elongate head and body. The snout, also, is 

 more truncate, due to the more vertical position of the premaxillaries. In hoyi the 

 mandible is frail, usually with a symphysial knob, and equals or exceeds in length 

 the upper jaw. 



The head is distinctly triangular in side view, and the body is always conspic- 

 uously deep, the depth often due to bloating. Hoyi, moreover, is a decidedly small 

 species. Few individuals grow larger than 230 millimeters, while zenithicus attains 

 a length of 300 millimeters. Numerous small specimens of hoyi usually are found 

 ensnarled in the twine of all the commercial nets of whatever mesh, while small 

 zenithicus seldom are taken in this manner. Zenithicus has fewer gill rakers on the 

 first branchial arch, more lateral-line scales, a smaller eye, longer snout, and shorter 

 paired fins. Those characters that can be expressed numerically are compared 

 below. The specimens of the two species, however, are not comparable for those 

 characters that deal with proportions, inasmuch as the hoyi are smaller than the 

 others, so that these differences probably are greater than they would be in specimens 

 of like size. 



