MISCELLANEOUS NOTES. 407 



of rushes which partly served to filter the direct rays of the sun. 

 Amongst and around the eggs were scattered the usual detached 

 fragments of herbage consisting chiefly of aquatic plants." 



Dr. Willey " did not see the adults, but the man said both parents 

 had been near the nest, the smaller of the two aggressively protecting 

 it : he called this one the female, not knowing that amongst fishes the 

 male is smaller than the female."^ 



The paper is based on the observation of four separate broods. The 

 egg had a diameter of about 1-25- mm. = 048" and over 100,000 to the 

 quart : nothing is said as to whether they float individually ^ or in agglutinat- 

 ed masses but apparently they are non-adhesive. They " lie immediately 

 below the surface film of water exposed to the quickening influence of 

 air and sun,'' and accordingly hatch out quickly. Dr. Willey thinks 

 " within three days after oviposition and j)erhaps within twentj^-four 

 hours." 



Gill mentions (op. cit. page 492) that the ophiocephalids mostly breed 

 twice a year : and the fact that the ova were found by Dr. Willey in 

 Ceylon on February 21st, May 28th and June * 1st seems to bear out 

 this theory. At any rate it is an indication of the fecundity of the 

 species and its adaptability to piscicultural methods. 



It is unfortunately impossible to reproduce the drawings Dr. Willey 

 has made to illustrate his researches. The eggs '•' owe their buoyancy to 

 the presence of a single large oil-globule which occiipies the greater part 

 of the ovum and is immersed in the golden yellow yolk." From this 

 condition " as seen with a simple lens at 5-30 p.m. we reach overnight 

 the stage * * * * * where the body of the embryo encircles 

 about two-thirds of the yolk like a belt. The surface view shows that 

 while the head is still oppressed to the yolk, the tip of the tail is 

 becoming folded off : the eye and the auditory vesicle are also present. 

 A few hours later the heart begins to beat and the tail to twitch." 

 And in a short time the embryo breaks the outer covering or vitelline 

 membrane and emerges as a larva or as trout breeders say an alevin 

 measuring 3'5 mm. or 0"137." 



" For three days the larvae remain at the surface of the water, resting 

 on one side of the yolk-sac up," and exhibiting when they swim 

 the helplessness usual in fish at this period of their development. 

 During the first day or most of it " the eyes are clear and devoid 

 of pigment " which makes it difficult at the first glance to distinguish 

 the fact that the fish have hatched out. But black pigment appears 

 in the eyes on the second day and by the third day the larvpe are 

 5 mm. (0'196") in length. They are still incapable of resting at the bottom. 

 On the fourth day the larvse are 6-75 mm. (•265") in length and can swim 

 freely at all levels : and on the fifth, the yolk-sac is absorbed. Dr. Willey 

 has recorded his observations in very full and lucid detail : he kept his fry 

 in a small enclosure in a glass tank and his records will be of the greatest 

 value to the biologist and fish culturist. For the purposes of this paper 



^ The g'eneralisation is not quite justified by facts. " In most fishes whose 

 males are differentiated by. marked secondary characters, so far as is known, 

 the male is larger than the female." Dr. T. Gill. Bull. Bur. Fisheries, U. S. A., 

 Vol. XXVIII, 1908, pag-e 1062 et seq. 



^ Salmon eggs = 5 mm. The largest pelagic eggs are that of the plaice = 

 1-6.5 to l'9o mm. 



^ Pelagic eggs are always non-adhesive and free (Camb. Nat. Hist., page 412.) 



* February is one of the coolest months in Ceylon: May the hottest up to 25th 

 when the rains are due. 



