85 
Tschikauia stands entirely apart by the character of the apical circuli, 
which are thick and widely spaced, as shown in the figure. They are 
frequently more or less broken up. In Darilius niloticus the apical cir- 
culi are extremely fine and regular, in complete contrast. The dorsal 
scales have the radii quite numerous, parallel, even more or less con- 
vergent, while those of the sides have them few, widely divergent, fan- 
like. In the Ischikawia the radii are divergent even on the dorsal scales. 
In the Zacco the radial system is as in Ischikauia, or very nearly so, but 
the circuli are absent in the apical field (a Gobio-like character), the 
transverse striae visible there being lines of growth. Thus the three 
fishes, having much in common, are easily separated by their scales. 
Fig. 1. 
Fig. 2. 
Fig. 1. Danio devario. Fig. 2. Danio aequipinnatus. 
Taking the scales alone, various Asiatic Danioninae (Danionina of 
Giinther) present the following characters: 
1) Danio devario H. Buch. Vithry (F. Day). Brit. Museum. (Fig. 1.) 
Scale broad, nucleus far basad; radial system as in Pseudogobio; apical 
circuli angled in middle line, approaching condition of Cerrhina. 
2) Danio aequipinnatus McClell. Slope of Byingyi Mtn., 2000ft., 
N. Lat. 20°, E. Long. 961/, (Oates). Brit. Museum (fig. 2). Characters 
essentially as in D. devario. The scale figured shows parallel apical 
radii, but scales with parallel and divergent radii occur on the some 
fish, as in Barilius niloticus. 
3) Barilius. See Proc. Biol. Soc. Washington, XXIII, p. 143, 
PI. 3, fig. 10. The scales of Asiatic Barilius can in general be distin- 
guished from those of Danio by the much more central nucleus. In B. 
gatensis (C. & V.) the nucleus is even apicad of the middle. In B. vagra 
(B. piscatorius) from Sind (F. Day) the nucleus is very far basad, and 
