356 R. S. CLARK. 



January and Febniary of this year, thougli less frequently in February. 

 The maximum was in January. The diameters of the eggs varied from 

 1-809 to 2-07 mm. One newly hatched larva measured about 6-9 mm. 

 These eggs were nearly all secured in inshore areas in Bigbury Bay and 

 off the entrance to the Sound in quite shallow water. 



Post-larval dabs are distributed generally over the area investigated, 

 though they occur in greater numbers between the twenty and thirty 

 fathom lines. The flounder shows a higher frequency in inshore areas, 

 while post-larvae of the merry-sole increase in intensity with the distance 

 from land. The maximum frequency for post-larvee of the dab lies in 

 May, of the flounder in April and May, and of the merry-sole in June. 



A specimen of P. microcephalus of 11 mm. shows no sign of meta- 

 morphosis, whilst in one of 12'5 mm. metamorphosis has commenced 

 (cf. Kyle,* p. 48, footnote). 



PLEURONECTIDJE. 

 Sub-fam. Bothin^. 



Arnoglossus sp. 

 An examination of several hundred adult specimens taken in the 

 Oiihona's otter trawl in 1913 proves conclusively, with the help of 

 Kyle's work,* the existence of three main species of the genus Arno- 

 glossus in the neighbourhood of Plymouth. Kyle relied on four principal 

 features for his segregation of the species, which he classified as : — 



(1) Structural Characters. 



(2) Dimensional ,, 



(3) Numerical ,, 



(4) Post-larval Characteristics. 



These are sufficiently clear and comprehensive to make the identifica- 

 tion of the three species at Plymouth comparatively easy. A. laterna 

 Walb. and A. im'perialis Raf. {A. lophotes Giinther) occur most abun- 

 dantly, while A. thori Kyle is comparatively rare. 



The character of the first few dorsal rays, the length of the head,, 

 diameter of eye, and length of ventrals seem quite good enough to 

 separate the three species already noted. 



The larval and post-larval material will be reported on more fully in a 

 later communication. There are considerably over a thousand specimens, 

 which represent nearly all the stages up to the metamorphosed condition. 

 A survey of Table 25 shows a maximum frequency in August and Septem- 

 ber, which, with the records for the earlier months, suggests a prolonged 

 * Rept. Danish Ocean. Exped., 1908-10. No. 2 (1913). 



