NOTES ON TELEOSTEAN OVA AND LARVAE. 



31 



size of about 5 cm., close up to the rocks on the shores of the Sound. 

 Post-larval stages of G. luscus, which appears to be the least abundant 

 of our four common representatives of the genus, are not infrequent 

 but are never numerous, and they disappear from the samples some- 

 what earlier than the other three.* Other species, such as G. morrhua 

 (cod) and G. vircns (coal-fish), are known, but are very occasional 

 spawners in this neighbourhood. 



The specific identification of the pelagic ova by the form and 

 pigmentation of embryo and larva is difficult and sometimes impossible, 

 owing to their great similarity. Pollack, indeed, is said to show no 

 yellow pigment at all in the embryo and early larva (14e, p. 171), while 

 the other three species above mentioned as common to these waters do 

 so to a greater or less extent. We cannot feel that we are on safe 

 ground here, however, in dealing with individual fishes on this point, 

 since the 6^. minutits larva is described by Raffaele from the Mediter- 

 ranean and by Holt from the west of Ireland as having only black 

 pigment, and in several cases the appearance of yellow chromatophores 

 has been noted as an accompaniment to an unhealthy condition 

 (cf. lid, p. 140). 



The impossibility of separating the species with certainty by refer- 

 ence to dimensions of the ova is indicated by the list which I give 

 below of measurements of eggs taken from ripe female fishes. 



* A general idea of the seasonal occurrence of the young fry may be obtained from the 

 following particulars taken from my records for 1909 of catches of tlie young-fish trawl : — 

 G. merlangits , . First specimens (5-10 mm. ) taken 28th April. 



„ . . Last ,, 



G. minutus . . First ,, 



,, . . Last ,, 



G. pollach'iiis . . First ,, 



,, . . Last ,, 



G. hiacu^ . . . First ,, 



,, . . . Last ,, 



t This is the diameter of the largest unfertilized ovarian egg observed. 



