157 



the other species. During the later stages the total absence of 

 yellow pigment, the transparency of the embryo, the late ap- 

 pearance of the black pigment and its characteristic distribution 

 make the diagnosis sure. The black pigment has a yellow colour 

 by reflected light, and observed against a dark background, of the 

 eggs at an advanced stage of development only the two patches 

 behiud the eyes and the large patch on the tail can be distinguished 

 and enable us to find them in a vessel even with the unaided eye. 



The issuiug larva is in the first place characterized by the 

 position of the oil-globule at the anterior end of the yolk-sac, it 

 being in most species placed at the hind end of the yolk-sac 

 near the vent ] ). In the second place the distribution of the black 

 pigment, a few scattered cells at the top of the snout, the two 

 dark patches behind the eyes, the black pigment on the oil- 

 globule and behind the rectum and the thick patch halfway down 

 the tail with a smaller spot almost at the end of the tail are of 

 a high diagnostic value. In later stages, when the yolk is rapidly 

 disappearing (fig. 7 and fig. 8) the scattered pigmentcells on the 

 trunk arrange themselves in a doublé row on the ventral side of 

 the body from the vent almost to the end of the tail. The thick 

 pigment-spot at the middle of the tail is diminishiug in size, but 

 was even in the larvae with almost no tracé of a yolk-sac left 

 still visible. The patch of pigment near the vent is increasing in size, 

 and very conspicuous. 



After having lost the yolk, the larvae die, and so the later 

 stages could not be studied; for though I captured several older 

 larvae (from 5 to 16 mM. in length) with the tow-net, which 

 presented a striking likeness to the larva figured in fig. 8, these 

 observations were not sufficiënt to make the diagnosis sure, and 

 so I will confine myself to the foregoing description of the larval 

 development. 



1) An anterior position of the oil-globule in the yolk-sac after hatching is found in 

 all the muraenoid-eggs provided with an oil-globule, in the eggs of mullus barbatus, of 

 mullus surmuletus, of cottus scorpius, of cottus bubalis, of coris Giofrecü(?), of coris julis, 

 of caranx trachurus. 



