EDWIN CHAPIN STARKS 



53 



It may be readily known from Plagioscion auratiis (Castelnau) by the 

 larger, rounder eye nearer to the anterior profile; by the narrower inter- 

 orbital space, which is less in width opposite the middle of the eye than 

 the vertical diameter of the eye; by the snout which does not overhang the 

 mouth so much, the lower jaw being scarcely, or not at all included; by the 

 longer pectoral, which is equal in length to the distance from the tip of 

 the snout to a point on the opercle midway between the preopercle and the 

 gill opening; by the first ray of the ventral, which, though a trifle longer 

 than the other rays, does not end in a filament. It has 2 or 3 more gill- 

 rakers on the lower limb of the arch, or 12 or 13; the preorbital is a little 

 narrower, the second anal spine a little longer, and the scales on the inter- 

 orbital space are ctenoid a little farther forward. Little difference exists 

 between these two species in the character of the teeth. The character of 

 the interorbital space will the most readily separate them. 



Most of these differences are well shown by the drawing of the type of 

 Plagioscion aiiratus and the drawing published by Steindachner of Plagio- 

 scion surinaviensis (Fische-Fauna des Magdalenen-Stromes. PI. I), though 

 there are also many differences there shown that do not exist owing to the 

 inaccurate drawing of the former species. 



TABLE OF MEASUREMENTS EXPRESSED IN HUNDREDTHS OF LENGTH. 



Length in mm. to caudal base. 



Head in lOOths of length 



Length of maxillary 



Long diameter of eye 



Width of interorbital space . . . 



Length of snout 



Length of pectoral 



Length of ventral 



Length of second anal spine . . . 

 Width of second anal spine .... 

 Length of fourth dorsal spine . 



Length of caudal 



Number of dorsal rays 



Number of anal rays 



175. Bairdiella armata Gill. 



A single specimen was taken in the market at Para. Comparing it with 

 specimens from Panama the snout is not so sharp, the spines of the pre- 

 opercle are more blunt and wider at the base, the mouth is a little more 

 oblique and more curved, the gill-rakers below the angle of the first arch 

 number 16 rather than 13, and the second anal spine is a trifle longer. It 

 appears probable that with more material the Atlantic form may be separable 



