94 CALIFOKNIA ACADEMY OF SCIENCES 



165. Centropomus robalito Jordan <l- Gilbert. 



Plate XIII, Fig. 25. 



Very abundant at Panama. 



Dr. Boulenger places this species in the synonomy of C. eiisiferug, and Jordan 

 and Evermann consider the two probably identical. They are easily distinguishable, 

 however, by the different size and the direction of the ridges on the top of the head, 

 by the larger serrations in C. ensiferus, the longer anal spines, and the rounded con- 

 tour of the spinous dorsal. The membrane between second and third anal si3ines 

 seems to be constantly blackish in ensiferus, and is usually pale in robalito. From C. 

 armatus, robalito differs strikingly in the longer, more flexible, dorsal spines, the 

 angular contour of the spinous dorsal fin, the ridges on head with the shape of the 

 enclosed areas, the shorter anal sjiines with the light interspinous membrane, the 

 more anterior position of the vent, the more numerous gill-rakers, the larger scales, 

 and the uniformly light color of the lateral line. The third anal spine fails to attain 

 the tip of the succeeding soft ray. The second spine extends beyond the third for 

 a distance equaling one-half to three-fourths the diameter of the eye ; it sometimes 

 attains the base of the caudal fin, but more frequently fails to do so. The dorsal 

 spines are long and flexible, the third little heavier than the fourth. The fin is 

 sharply angulated at the tip of the third spine, which usually reaches a straight line 

 joining the tips of the succeeding spines. The second spine is very short, contained 

 4 to 44^ times in the third. The distance from the vent to the base of the first anal 

 spine nearly equals that from tip of snout to hinder margin of orbit, varying a little 

 from that measurement in either direction. The spines on the margin of the pre- 

 orbital and preopercle are distinct and strong, but less so than in armatus. 



The median pair of ridges on head are stronger than in any other species, and 

 enclose a narrower space, which is widest opposite the posterior ends of the ridges 

 and is regularly wedge-shaped, the ridges meeting at a point opposite the nostrils. 

 The gill-rakers are long and slender, the longest two-thirds the diameter of the orbit. 

 They are more numerous than in armatus, 7 or 8 movable ones on the vertical limb 

 and 15 or 16 on the horizontal limb, with 2 or 3 rudiments at each end of the series. 

 There are 40 to 49 scales in the lateral line in advance of the base of the caudal fin, 

 and o or 6 scales in a vertical series between the lateral line and the middle of the 

 second dorsal. The lateral line is uniformly pale. 



In the fresh state the ventrals are rich golden yellow, whitish at the base, with 

 white pigment at tips, best marked on the inner rays. Anal lemon-yellow, including 

 the membrane between the spines, which is rarely dusky; the base of the fin and 

 the la.st two rays are translucent. The spinous dorsal is translucent dusky, not dis- 

 tinctly black; the soft dorsal similar, translucent at base. The caudal is dusky trans- 

 lucent, slightly tinged with straw color, the latter best marked on the lower lobe. 

 The pectorals are translucent. 



