LARViE, ETC., OF OPHIOCEPHALUS STRIATUS. H9 
external yolk-sac which persists much longer than the yolk-sac of 
Ophiocephalus . “ By the tenth day after hatching the larvse are 
able to drag their yolk-sac to the surface of the water, when they 
take a gulp of air into their lung-like swim-bladder and fall again to 
the bottom, on reaching which they again start for the surface with 
unceasing regularity, so that when looked at from above, the nest 
of Gymnarchus , with its swarm of scarlet-bearded [referring to the 
external gills], yolk-hampered larvse, presents a most amazing- 
spectacle. ” (Budgett, op. cit. pp. 131-32.) 
The circulation of the blood in the larvae of Ophiocephalus 
conforms to the larval Teleostean type of circulation and presents 
several interesting characteristics, chief among which are the direct 
junction, during the early days of larval life, between the aorta and 
the caudal vein ; the yolk-sac circulation which is intercalated in the 
subintestinal system in a manner analogous to the relations of the 
hepatic coecum in Amphioxus ; the subin testinal vein itself, which, 
as was pointed out long ago by Balfour (op. cit. p. 651), recapitulates 
an ancient pre-piscine organization ; lastly, the reversed current of 
the posterior cardinal blood, which, instead of flowing forward 
towards the heart, flows backwards to join the subin testinal system, 
so that the aortic blood and the cardinal blood is seen to be flowing 
in the same direction. 
Lastly, it may be noted that although, as I believe, the floating 
eggs of “ lula ” are unique amongst freshwater fishes, so far as the 
available records go, yet they present some analogy with the eggs 
of some species of marine fishes. Thus the transparent eggs of the 
greater weever (Trachinus draco), with a diameter varying from a 
little less to something over one millimetre, have a single large oil- 
globule and float at the surface of the sea. Four or five days after 
oviposition the embryos are hatched ; and four or five days after 
hatching the yolk has become absorbed. The buoyancy of the yolk- 
sac causes the larvae to float helplessly in the water for some time 
after hatching, with the yolk-sac uppermost.* 
Practical Considerations. 
The usefulness of “ lula ” as a source of food-supply for the low- 
country of Ceylon, together with the fact that attention is now being 
drawn to the maintenance and replenishment of the stock of fishes 
in the rivers and tanks of this country, makes it incumbent upon us 
to examine the practical bearing of the foregoing observations and 
* J. Boeke. On the early development of the Weever Fishes. Tijdschr. 
Nederland. Dierk. Ver. (2) VIII., 1903, pp. 148-57, PI. VII. I have not 
seen the original paper, but it is quoted by Dr. Theodore Gill in “ Life histories 
of Toadfishes compared with those of Weevers and Stargazers,” Smithsonian 
Miscellaneous Collections, Quarterly Issue, Vol. III., Part 4, Washington, 
1907, p. 421. A subsequent paper by Boeke on “ The later larval develop¬ 
ment of Trachinidse” appeared in the above-named journal, Vol. X., 1907, 
pp. 245-54. 
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