\ 



75 



customers who are careful they readily select the two species of 

 Osmerus, as being more delicate than those of AtJiejinopsis. 



Atherinopsis tenuis, (Ayres). Fig. 19. Form elongated, some- 

 what compressed, very slender, the greatest depth being about one- 

 seventh of the total length. 



Head pointed anteriorly, its length constituting a little more than 

 one-sixth of the length of the fish ; mouth rather small, upper jaw 

 projecting beyond the lower, its border formed as in the other 

 species of the genus, by the intermaxillaries ; teeth exceedingly 

 minute ; depth of the head across the middle of the eye about 

 equal to half the greatest depth of the body ; diameter of the eye 

 one-fourth the length of the head ; eye distant rather more than 

 its own diameter from the tip of the upper jaw. 



Scales firm and hard, like those of Atherinopsis qffinis, abou 

 twelve rows vertically ; each scale beautifully crenate (not dentate) 

 on its posterior border, appearing as though provided Avith a row of 

 minute accessory scales ; scales covering the body and head, 

 excepting the space anterior to the eyes. 



Branchial apertures continuous under the throat ; branchial rays, 

 six. 



Colors similar to those of the other species of the genus on our 

 coast, greenish brown above, silvery on the sides and beneath, with 

 a bright silvery band occupying the middle of the side from the 

 head to the caudal fin ; pectorals, dorsals, and caudal fin blackish 

 brown, ventrals and anal pale. 



First dorsal very small ; its length, which is a little less than its 

 height, being only one-sixth of the length of the head ; its origin 

 is about equidistant between the tip of the caudal fin and the ante- 

 rior border of the eye ; it is separated from the second dorsal by a 

 space equal to twice its own height. 



Second dorsal trapezoidal in form, its posterior border being a little 

 more than half as high as the anterior ; its length, which is a little 

 greater than its anterior height, equals half the length of the head ; 

 it is separated from the caudal by a space about equal to the depth 

 of the fish. 



Anal fin elongated, its length being a very little less than one- 

 fourth the length of the fish ; its origin is a little in advance of that 

 of the first dorsal, being about on the middle line of the entire 

 length ; it is concave in its margin, its height anteriorly being 

 about half the length of the head, while that posteriorly is some- 

 what less, and tiiat of the mesial portion decidedly less still. 



The pectorals are pointed ; their height, which is not quite four 

 times their length, being equal to the length of the head. 



The ventrals, which are rounded, have their origin about even 



