ICHTHYOLOGICAL CONTRIBUTIONS. 329 



shape of the snout and the position and structure of the mouth. 

 The edge of the upper lip on the right side is curved, as in the 

 adult sole ; teeth are absent from the jaws on the right side^ present 

 in the lower jaw on the left. The intestine, however, does not reach 

 its adult condition till a much later period. In this stage it has 

 only one coil, and the posterior part does not extend backwards 

 behind the median body-cavity. The coloration is not reproduced 

 in the figure : it consisted of black and orange specks (chromato- 

 phores) and more diffuse patches of lemon-yellow. The pigment 

 was not arranged in the markings which characterise the adult, and 

 which are already visible in the early post-larval stage figured in 

 my treatise. On the body and head the specks were pretty 

 uniformly distributed, but on the dorsal fin there were three 

 pigmented regions, one at the anterior end, one in the middle, and 

 one near the posterior end. On the post-anal fin there was only 

 one pigmented area of considerable extent, opposite the posterior 

 area of the dorsal fin. 



In my Treatise on the Sole I was only able to figure the newly 

 hatched larvje and the earliest post-larval stage. Three other larval 

 stages were figured and described in vol. ii, No. 1 of this Journal 

 (pi. iii). The stage here described is intermediate between the 

 latter and the first post-larval stage, and fills up an important gap 

 in the series, although additional intermediate stages are still required. 

 My use of the terms larval and post-larval differs from that adopted 

 by Professor Mcintosh and some of his pupils, who restrict the 

 former term to the stages prior to the absorption of the yolk, and 

 call subsequent stages post-larval. I cannot see any justification 

 for this application of the terms. A fish is a larva until the most 

 important organ-systems of the adult, such as the permanent skeleton 

 and fins, are developed. 



3. A Larval Stage op the Mackerel. 



Plate XIV, fig. 1. 



In the first number of the current volume of this Journal (vol. 

 ii. No. 1, p. 71, pi. iv, fig. 7) I described and figured the newly 

 hatched mackerel larva. Last year I made further experiments in 

 hatching and rearing the larvae of this species from artificially 

 fertilized eggs, using a hatching box of Captain Dannevig's pattern. 

 I succeeded in keeping some of the larvae alive four days after 

 hatching, and the condition then reached is shown in fig. 1. 



In this stage the yolk is almost entirely absorbed^ but a remnant 



