LARVAE, ETC., OE OPHIOCEPHALUS STRIATUS. 
115 
As already indicated, the fortieth day after hatching maybe taken 
to mark approximately the end of the larval development, in so far 
as this is denoted by the condition of the fins (Figs. 15 and 16). 
As soon as the fin-rays are properly laid down and their outlines 
darkened by pigment, the amount of pigment in the dorsal and anal 
fins becomes equalized. The other characters at this stage are the 
broad yellow lateral stripe ? a short yellow band in front of the 
dorsal fin culminating in a shining golden occipital spot, and a 
golden‘yellow mark over each eye. 
The subjoined table gives a summary of the chronological data 
which I have been able to ascertain regarding the external features 
of the development of Ophiocephalus striatus :— 
Days after 
Hatching. Total Length. 
Principal Events. 
1 
2 & 3 
4 
7 
12-15 
28 
37 
40 
.. 3*5 mm. 
. * 4 * 5 to 5 mm.. . 
6 ‘75 mm. 
.. 7 mm. 
6*75 mm. 
8-10 mm. 
10 m.m. 
.. 10*25-13 mm... 
Yolk-sac circulation established; 
pigment cells develop their black 
colouration; pigment begins to 
appear in eyes. 
Pectoral fins arise ; mouth opens, and 
respiratory movements commence. 
Larvae leaving the surface and swim¬ 
ming freely at all levels. Bright 
yellow spots over eyes. 
Larvae swarming and turning in unison 
at the slightest concussion. Caudal 
cartilages appear. 
Posterior end of notochord bends up. 
Caudal rays jointed and articulated 
with the basal cartilages. Larvae rise 
to surface to take air. 
Primordia of dorsal and anal rays. 
Rudiments of ventral fins appear. 
Dorsal and anal fins separating from 
caudal. 
63 
73 
17 mm. 
.. 25 mm. 
The fry now hide in the mud. 
With reference to the above it is to be noted that after the absorp¬ 
tion of the yolk about the fifth day after hatching, when the larvae 
begin to feed independently, the daily growth begins to vary ; and 
the variation is probably the greater on account of the larvae having 
been reared in captivity. It has been similarly noticed that in the 
case of the trout, larvae of equal ages occur in very different stages 
of development.* Only one larva was examined on the thirty- 
seventh day. The striking increase in length to the extent of a 
* Compare E. Goeppert. Die Entwicklung des Pankreas der Teleostier , 
Morph. Jalirb., XXI., 1893, p. 90. 
