362 E. S. CLARK. 



comparatively easy. Of the four species, S. variegata (thickback) occurs 

 most frequently. The maximum number of post-larvse was in June. 

 They were taken in diminishing numbers on to August. This coincides 

 with the period recorded by Petersen for the capture of his post-larval 

 specimens — May to July. Records of S. lutea are confined to July and 

 August, but the number of individuals is extremely small. S. lascaris 

 occurred in increasing numbers from July to September, after which 

 month they disappeared from the pelagic hauls. S. vulgaris post-larvse 

 were taken in May and June, but were extremely few, and by no means 

 representative of the number of individuals in the neighbourhood. 

 S. vulgaris and S. lutea show a higher frequency inshore at depths of 

 about ten fathoms or less, while S. variegata and S. lascaris have a dis- 

 tinctly low frequency for this area. The maximum for these two species 

 lies between the twenty and thirty fathom lines. Both were taken beyond 

 the thirty-fathom line, and it is possible, at least for S. variegata, that 

 the frequency may increase with the distance from land. Our knowledge 

 of the life-history and developmental stages of S. vulgaris and S. lutea is 

 fairly complete. Kyle has remarked on the greater breadth of similar 

 forms of S. lutea from the more southern waters to those from the 

 North Sea. My specimens of S. lutea show a distinct gradation from 

 the one to the other. The greatest breadth (without the dorsal fin) 

 ranges from about 25% to slightly over 40% of the total length. 



S. variegata Don. 



Post-larval S. variegata are known chiefly from the researches of 

 Petersen,* whose specimens were captured mostly over depths from 

 1000 to 4000 metres, though he recorded captures from 53 and 113 

 metres. The series ranged from 7 to 18-3 mm. in length. At the latter 

 length, metamorphosis was a long way off completion. It seems peculiar 

 that my specimens are equally well advanced in development, but at a 

 much smaller size. My post-larvse of almost 4 mm. are closely identical 

 with Petersen's 7 mm. post-larva, and just as far advanced in develop- 

 ment. At 11 mm. in my material metamorphosis has already reached 

 almost half-way. There is at a length of 11 mm., the largest post-larva 

 in my collection, a distinctive difference in pigmentation from Petersen's 

 metamorphosed specimen. The pigment is not confined to the fins, 

 interspines, and margin of the abdomen and head, but also scattered 

 universally over the whole of the body, not as tiny black dots, but as 

 fairly stout stellate chromatophores of moderate size. 



* Medd. fra Komm. f. Havund. Serie Fisk. Bind III, Nr. 1. 1909. 



