PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 321 
orbital space strongly convex transversely. Cheeks with three rows of 
scales. 
Gill-rakers rather small, but longer and stronger than in D. furcatwn, 
the longest about one-third the diameter of the orbit. 
_ Scales moderate, averaging rather smaller than in D. furcatum, about 
5-70-13. 
Spinous dorsal comparatively low, the first spine short, the others 
rapidly increasing to the fifth, after which the others are nearly of equal 
length, but gradually increasing to the last. The first soft ray is a little 
higher than the highest spine. The other soft rays are gradually short- 
ened. 
The caudal fin is deeply forked, the lobes being about equal. In D. 
Jurcatum the upper lobe is evidently the longer. Anal fin low, its spines 
moderately developed. Pectorals not reaching to the tips of the ven- 
trals, which scarcely fall short of the first anal spine. 
Fin rays: D: X, 23; A. HI, 29. 
Coloration light dusky olive above, silvery below, with pearly reflec- 
tions. Scales above the axis of the body each with a golden-red spot 
at base, the outer margin of the scales tinged with light blue. These 
spots fade in alcohol, but are conspicuous in life, forming reddish 
streaks along the rows of scales. 
Membrane of dorsal, anal, and ventral fins light olive-green. Traces 
of a dark shade on upper part of first rays of soft dorsal. No black at 
base of dorsal. A distinct black blotch on upper third of first eight- 
rays of the anal. Ventrals broadly tipped with reddish black, as in Hyper- 
proropon argenteus. Pectorals and caudal entirely plain, the black edg- 
ing to the latter fin, characteristic of D. furcatum, being entirely want- 
ing. Premaxillaries and end of snout distinctly dusky. Iris silvery, 
reddish above. 
In Ditrema furcatum the color is nearly plain, pale, olivaceous, and 
silvery, the scales with bright reflections, but without distinct red mark- 
ings. The sides are more silvery than in D. atripes, and there are more 
black punctulations. The naked portion of the base of the soft dorsal 
is black. There is no dark shade on the ventrals, and the caudal is dis- 
tinctly margined with black behind. The dark anal spot is similar in 
the two species, but it is sometimes wanting in D. furcatwn. 
The species Ditrema argyrosoma (Phanerodon argyrosomus Gill, Hm- 
biotoca argyrosoma Girard), if distinct from Ditrema furcatum, is un- 
known to us. It differs, according to Girard, in having the anal IIT, 24, 
but the types had been mutilated and this count may, perhaps, be erro- 
neous. 
Proce. Nat. Mus. 80. 
21 Oct. 27, 1880. 
