232 TREUBIA VOL. II, 2—4. 
spots of the anterior and posterior edges, a larger black patch, which in 
the caudal half of the fin may end in a number of distally situated smaller 
black dots. The distal end of the dorsal fin and especially its anterior 
edge and likewise the dorsal and ventral edges of the caudal fin are 
coloured a more or less clear red in the females, from an accumulation of 
lipochrome-chromatophores. Distally again from this red the dorsal fin may 
finally display a band of sparsely strewn black chromatophores. In addition 
both in males and females nearly the whole of the remaining parts 
of the dorsal and caudal fins bear scattered lipochrome- and melanin- 
chromatophores. 
However in the males the antero-distal part of the dorsal fin and the 
dorsal and ventral edges of the caudal fin are characterized by an other 
colouring element instead of the chromatophores. For in those places 
the males possess, as the miscroscope reveals, a great number of dull, 
irregularly rounded corpuscles, which reflect a very pale blue light, and 
must certainly be classed among the iridocytes. It is owing to these pale- 
blue corpuscles that the bluish-white more or less phosphorescent appear- 
ance of the antero-distal part of the dorsal fin and the dorsal and ventral 
edges of the caudal fin in the males is produced. Also the posterior edge 
of the caudal fin may possess such pale-blue corpuscles, in which case the 
whole distal edge of the caudal fin displays the shining bluish-white tinge. 
The red colour of the antero-distal part of the dorsal fin and of the 
dorsal and ventral edges of the caudal fin is not always equally marked 
in the females; it may even be but faintly perceptible to the naked eye. 
The bluish-white shining colour on the corresponding parts of the males 
is usually clearly distinguishable. This colour however is not yet developed 
in the male specimens below a certain age. The smallest kepala timah 
in which I found a number of the dull irregularly rounded pigment 
corpuscles in the antero-distal end of the dorsal fin and at the cranial end 
of the dorsal edge of the caudal fin, was 2.8 cM. long, whereas an adult 
male kepala timah measures nearly 6 cM.. 
The rest of the dorsal edge and specially the ventral edge of the 
caudal fin were still coloured red in this little specimen of 2.8 cM. in length, 
just as is the case in females, whilst the irregularly rounded pigment- 
corpuscles already present reflected not a pale-blue but a greenish yellow 
light. However it may also happen in bigger male individuals that the 
antero-distal part of the dorsal fin and the edges of the caudal fin are 
not coloured a light blue but a light citrine yellow. I once found a male 
kepala timah 5.5 cM. long in which this was the case. 
Viewed from above the females are further often distinguishable . 
at first sight, because the flanks of a female kepala timah bearing 
ripe eggs are somewhat distended immediately behind the pectoral fins. 
Such females with ripe eggs and distended flanks may be met with in 
the empangs all the year round. With these animals one can also see 
