LAKVAL AND POST-LARVAL TELEOSTEANS. 359 



Sub -f am. Rhombin^. 



ScophtJuilmiis norvegicus Gthr. S. unitnaculatus Bnp. 

 Zeugopterus punctatus Bl. 



ScopJithalmus norvegicus Gthr. 



This is the commonest topknot of the district. The records of the 

 pelagic stages in Table 25 indicate an indefinitely prolonged spawning 

 period from March or April to July. The maximum for the post-larvse 

 lies in June, so that the densest spawning month is most probably May. 

 Frequency is highest between the twenty and thirty fathom lines, and 

 lowest beyond the thirty-fathom line. 



TABLE XVI. 

 Record of Scophthalmus unimaculatus Bnp. 



The adult one-spotted topknots are of exceedingly rare occurrence 

 at Plymouth, so that the capture of these three post-larvse is all the 

 more interesting. They were all secured beyond the twenty-fathom line, 

 from 16th June to 15th July, and were identified with the help of Peter- 

 sen's descriptions and figures of specimens, ranging from 6-7 to 8 mm. 

 in length. 



The oldest stage has a length of 11 mm., and it is still perfectly sym- 

 metrical. The concavity of the snout is well marked, and the dorsal fin 

 is almost on a level with the posterior margin of the orbit. The diameter 

 of the eye is contained about three times in the snout length. Ventrals 

 are developed, though still small. The caudal fin is rounded and almost 

 fully developed and about seventeen rays can be counted. The two pairs 

 of otocyst spines are quite conspicuous, though not so prominent as in 

 Z. punctatus. 



Small dendritic chromatophores are scattered over the head and body, 

 much as in S. norvegicus, though practically absent from the orbital 

 region, and less dense on the interspinous region. There is a suggestion 

 of the pigment on the unpaired fins beginning to concentrate into bars. 



