EGGS AND LARVAE OF TELEOSTEANS. 123 



August. It has also been observed on the British coast, but I have not myself 

 met with it. A more complete description, with better figures, is given 

 by Agassiz and Whitman in Pelagic Stages. The egg is large, 175 mm. 

 in diameter, and has a single immense oil globule "4 mm. in diameter, of a 

 transparent copper colour. Black chromatophores are developed very early, 

 and are aggregated chiefly about the ventral side of the embryo, present in less 

 abundance on the surface of the yolk sac, round the oil globule, and on the tail. 

 In the newly hatched larva the yolk sac is globular, and very large in compari- 

 son with the body ; the oil globule is ventral and posterior ; the rectum 

 is immediately behind the yolk ; the eyes are deeply pigmented ; the notochord 

 multicolumnar ; the pelvic fins not developed. The successive forms of the 

 larva, which is up to a late stage pelagic, are described and figured in Young 

 Stages, iii. Agassiz points out the resemblance, both in the character of the 

 spawn and the structure and development of the larva, between Lophius and 

 Fierasfer, comparing the long anterior dorsal spine in the former, which is 

 a permanent organ, but develops at a very early stage, to the vexillum 

 of Fierasfer, which is a temporary appendage disappearing completely in the 

 adult. It seems probable that in the Fierasfer larva the vexillum is morpho- 

 logically derived from a fin ray, as are the appendages in Lophius. 



The male of Antennarius, another species of this family, a pelagic fish, 

 makes, according to Gunther, a nest, and guards the eggs deposited in it. We 

 have thus in this family a series of steps in the transition from ordinary littoral 

 adhesive ova to typical pelagic ova. The ova of Antennarius are probably 

 adhesive, and are deposited in a pelagic nest. The ova of Lophius are also 

 adhesive, but float as a detached mass unprotected by an apparatus formed 

 from pelagic algae. If the ova of Lophius were separate, instead of adhering 

 together in a mass, they would be typical pelagic ova. 



Fam. 11. Cottid^e. 



The question of the ova of Cottus has been discussed in a previous section. 

 The pelagic ova of Trigla gurnardus have been described.* 1 In this family we 

 have a greater difference between the ova of closely allied genera than in the 

 preceding, for the eggs of Cottus are typical examples of littoral adhesive ova, 

 while those of Trigla are typically pelagic. Sundevall (Joe. cit.) gives an 

 account of the development of Cottus gobio and Cottus quadricornis. The eggs 

 of the former species are deposited in May. The larva twenty-four hours after 

 hatching was 8 mm. long; there was a single oil globule in the yolk, and the 

 rectum was in contact with the yolk sac. The larva of Cottus quadricornis is 



* u 



Yolk and Gastrula," J. T. Cunningham, Quart. Jour. Micr. Sci., 1885. 



