230 TREUBIA VOL. II, 2—4. 
It then appears that, as is usually the case, the green-brown colour 
of the back arises from the combined effect of black melanin-chromato- 
phores and yellow lipochrome-chromatophores in the deeper layers of the 
skin, above which in the more superficial layers of the skin (in the epidermis ?) 
a number of smaller star-shaped melanin-chromatophores occur. Anteriorly, 
on the snout this superficial layer of small chromatophores is entirely absent. 
The fine dark longitudinal dorsal line, if present, results from a local 
accumulation of chromatophores. Among these chromatophores there also 
occur on the dorsal side of the kepala timah a few pale-violet-blue and 
light-green to gold-yellow glistening iridocytes; along the sides the numbers 
of chromatophores diminish, whereas the iridocytes grow more numerous, 
their presence effecting the metallic tinges of the sides of the body, of the 
operculum and of the ventral side of the tail. The white colour of the 
belly before the ventral fins depends upon the absence of chromatophores 
and the presence of a dense layer of iridocytes forming the so-called 
argenteum. 
The black bands along the fore-edges of the scales are robe by the 
bigger deeper-seated chromatophores; the little red patch that may occur 
in the middle of these pigment bands is an accumulation of red lipochrome- 
chromatophores. 
Above the occipital spot which is situated centrally beneath a large 
cycloid scale, there occur as regards the chromatophores of the skin, only 
some very few of the superficial small melanin-chromatophores and these are 
chiefly situated above the edges of the spot. Above those edges again in 
the deeper layers of the skin the only chromatophores met with are some 
lipochrome-chromatophores. The deeper lying larger melanin-chromato- 
phores are entirely absent from the skin over the white spot. 
The little spot itself and the melanin- and lipochrome-chromatophores 
that may obscure it, are situated just under against the completely trans- 
parent dorsal investing ')-bones of the skull, in the exomeninx. The 
white of the spot is formed by a dense compact layer of iridocytes. This 
may be observed when a kepala timah is allowed to die on the dry under 
the binocular microscope; for then the iridocytes making up the spot begin 
to show metallic colours. One can also open the skull of a kepala timah 
with a couple of fine needles and remove the exomeninx from the ventral 
side of the dorsal investing-bones of the skull; the exomeninx then proves 
to contain black and yellow chromatophores together with numerous 
iridocytes. 
Also in a live Haplochilus javanicus the pigment of the exomeninx is 
clearly distinguishable from the outside. Haplochilus javanicus has on the 
head, immediately behind the eyes and situated just laterally of the sagittal 
plane touching the eye-ball on the median side, two green and blue 
metallic hued crescent-shaped patches, whose convexity is turned towards 
') investing- or membrane-bone = dekbeen. 
