752 Proceedings of the Royal Irish Academy. 



VI. — On Young Stages of Teleosteans. By J. T. Cunningham, M.A. 



The specimens were taken in a tow-net diu'ing April and May, 

 1895, by Mr. E. T. Browne. 



Pleuronectes flesus (Common Flounder). 



One specimen ; left eye still on lower surface, but slightly 

 dislocated towards the dorsal edge. Ventral fin rays, 38 or 39 ; 

 dorsal, 63 or 64. Mouth shows characters of genus Pleuro- 

 nectes. 



Zeugopterus punctatus (Largest Top-knot). 



(1) Early stage, with no indications of fin-rays in the fin 

 membrane ; two large periotic spines on each side, and five 

 bands of pigment on the fiji membrane. ; 7 '5 mm. long, as in 

 fig. 94, pi. xii., of Holt's Memoir in Sci. Trans. Eoy. Dublin 

 Soc, vol. v., ser. 3. 



(2) Symmetrical stage, with one dorsal periotic spine, the 

 ventral one not visible. Dorsal and ventral fin rays beginning 

 to appear. Ventral caudal rays somewhat advanced, but ter- 

 minal part of notochord scarcely bent up ; 12' 5 mm. long. 



Zeugopterus unimaculatus (One-spotted Top-knot). 



( 1 ) Symmetrical stage before the appearance of fin-rays ; 

 yolk all absorbed ; 6 mm. long. 



(2, 3) Symmetrical stage, with ventral fin rays just indicated. 

 over 64 in number; dorsal rays in same condition. Minute 

 protuberances along edge of opercular bone and behind octocyst, 

 One specimen younger than the other ; 7 mm. and 8 mm. long. 



(4) Advanced stage, with eyes on left side of head ; fin rays 

 advanced in development ; ventral, 67 or 68 in number ; 8 mm. 

 long. 



It is worth noting that Holt obtained a numerous series. 

 of these same larval stages in the course of the Irish Suiwey 

 His specimens were taken in bottom tow-nets, coast of Donegal, 

 May, 1891. It would appear that the species is fairly common 

 in Ii'ish bays, and that its young are reared in the bays, for 

 which reason they are so commonly taken in tow-nets. 



