The differential distribution of cones in the various regions of the retina of the fishNemipterus japonicus (Bloch) was studied. In tangential section two types of cones are observed viz single and double cones, double cones being greater in number than single cones. Of the total cones, double cones constitute 86% while single cones constitute only 14%. In most of the retinal regions, cones are in the square mosaic pattern. The temporal region has greater number of cones than the other retinal regions which were studied. The correlation coefficients for the temporal region with all other regions are invariably positive.
The test shows that there is no significance between the eyes whereas significance is observed among the various retinal regions. The pattern of cone arrangement agrees with the bottom dwelling habit of the fish. The shape of the eye is modified by being slightly ablong with comparatively longer anterio-posterior axis. The retinal cup is more hollow at the temporal region than at the nasal region.