146 
bulletin of the bureau of fisheries. 
Suborder Percesoces. 
ATHERINIDiE. Silversides. (PI. xxxvi, fig. 25.) 
For a general account of the scales of this family, see Proceedings of the Biological Society of Wash¬ 
ington, volume xxiii, pages 47-48. The genera Kirtlandia and Menidia are discussed, and the resem¬ 
blance to the scombrids is noted. All the scales except Kirtlandia have distinct basal radii, with the 
lower margin usually scalloped; the laterobasal angles are distinct, and there are distinct apical radii 
in some forms, as Chirostoma. The following key separates the species before me: 
Lateral and apical circuli alike and continuous, the circuli very widely spaced; scale very small, 
less than i}4 mm. broad, strictly cycloid; no apical radii; basal radii well developed, about 5 
or 6; laterobasal angles rectangular. 
Atherinops regis Jenkins & Evermann. (Algodones Lagoon, Mexico; Albatross) 
Lateral circuli strongly differentiated from apical, or the latter modified or partly suppressed... 1 
1. Apical margin scalloped or lobulate. 2 
Apical margin entire. 3 
2. Scale much broader than long; basal margin undulate, with a single large lobe; apical margin 
irregularly lobed, with traces of radii; basal radii reduced to one or two broad folds, no true 
radii; apical field without sculpture, but across the middle of the scale, apicad of the regular 
circuli, is an area of very fine longitudinal lines, in the middle on the apical side breaking into 
very fine labyrinthiform markings. Kirtlandia laciniata (Swain). (Chesapeake Bay, Va.) 
Scale little (sometimes not at all) broader than long; basal margin more or less angulate in the 
middle; apical margin finely irregularly scalloped, with evident though slender radii; basal 
radii about 7 to 10, well developed; lateral circuli very widely spaced, but apical field 
with extremely fine transverse circuli, which are much broken, and in the nuclear area mostly 
reducedto dots.. Chirostoma crystallinum Jordan & Snyder. (Lake Chapala, Mexico; J.N. Rose) 
3. Basal radii distinct; lateral circuli very widely spaced; apical circuli transverse, very dense, 
more or less broken, toward the nucleus reduced to granules; apical radii very slender, 
irregular, not always evident. 
Menidia peninsulce (Goode & Bean); M. menidia (Linnaeus); M. notata (Mitchill) 
Of this series, Chirostoma is possibly the most primitive, but Atherinops stands apart and has the 
primitive character of continuous, uniform circuli in the lateral and apical regions. Kirtlandia seems 
much modified, but hardly from a Menidia- like basis. Probably Atherinops and its allies should form 
a distinct subfamily. 
The scales of Menidia notata described in my paper cited above were not adult; other scales from 
the Bureau of Fisheries collection are about 3.5 mm. broad, with the apical margin subangulate or 
roof-like in profile. 
MUGILIDAk Mullets. 
The white mullet, Mugil curcema Cuvier & Valenciennes, from the collection at Woods Hole, has 
large rounded scales, with a straight, medially emarginate base; length about 9.5-10 mm; breadth 
11-11.5; basal radii few, crowded about the middle of the scale; nucleus apicad of middle; lateral 
circuli coarser than basal; apical margin minutely ctenoid, the apical region with the minutely imbri¬ 
cated structure of typical ctenoid scales. 
Here, then, we first meet with the typically ctenoid type of scale, as developed among the Acan- 
thopterygians. The ctenoid scales of certain Characinidae are of an entirely different character. 
There is no evident connection between the scales of Mugil and those of the Atherinidae. 
SPHYR7ENID7E. Barracudas. . 
The scales of Sphyrcena are very peculiar, and wholly unlike those of the Atherinidae or Mullidae. 
5. picuda Bloch & Schneider, from Tampa, Florida, has relatively large reddish scales, about 7 mm. 
long and a little over 6 broad, the lateral and basal margins gently convex, laterobasal comers obtuse, 
the apical region thin and without sculpture. The sculptured part of the scale has throughout extremely 
dense circuli, which, except in the upper lateral region, are interrupted by very numerous radii. The 
radii are very uniform, about 5 to 9 to a millimeter of the margin. The midmost circuli are not only 
divided into short sections by the radii, but the sections themselves are cut at intervals by very fine 
