232 



Part III. — Thirteenth Annual Report 



5. On the Post-Larval Stage of Crystallogobius Nilssonii. 



In tho Ninth Annual Report of the Board, Part III., p. 332, an unknown 

 elongated post-larval form, with prominent teeth and long pectorals, pro- 

 cured on the 20th July 1889, was described. A further examination 

 of this young fish, which was only 7 mm. long, shows that in all 

 probability it is the post-larval stage of a male of Crystallogobius nilssonii, 

 which, at that date, had only once been found in Scotland, viz., by Mr 

 Edward, in a rock- pool at Banff. The very early stage at which the 

 special sexual characters occur in this species is interesting, yet Dr Day 

 considered that in the young males the head is more pointed, indeed, 

 almost as in the females — in which the jaws are short, straight, and 

 toothless. It is clear, however, that such a statement requires amend- 

 ment, especially the supposition that the teeth ('canines') are only 

 developed as maturity is reached. In the small example from St 

 Andrews, it was the presence of these characteristic teeth and the shape 

 of the mandible that attracted attention, and yet the larval marginal fin 

 was still present. The description given in the Ninth Report may be 

 supplemented by the remark that in the adult male the pectoral fins are 

 remarkable for their " broad (multiradiate) and somewhat lobate form, 

 " with their semi-circular muscular root, and elongated, roundish shape. 

 " When expanded the pectoral fins are as deep as the body." In life they 

 are boldly speckled with black on a yellowish ground, the latter being 

 brightest interiorly. The remarkable coloration of these fins in the post- 

 larval stage is an addition to the series in developing Teleosteans. 

 When the eyes of a fresh form are examined from above they are finely 

 iridescent and greenish-blue ; even when seen laterally they are silvery 

 with a bluish sheen. Since this specimen was captured Mr Cunning- 

 ham has procured many adults of both sexes near the Eddy stone 

 Lighthouse, while Mr Holt has been equally successful off the West 

 Coast of Ireland, and on the East Coast of England. It appears to be 

 generally distributed round British shores, though the adults have not 

 yet been secured here. It is sometimes found in as great abundance 

 in Norway as in the South of England. The authors (Fries, Ekstrdm 

 and Sundevall), of the recently published work on Scandinavian Fishes, 

 observe that June is approximately the spawning season of this species, 

 and the development of the post-larval example would appear to point to 

 May or early June as the probable period on our shores. 



6. On a Post-Larval Form resembling a Goby. 



In the account of the Pelagic Fauna of the Bay of St Andrews in 

 1888, a post-larval fish, procured off the Tents' Moor on the 20th 

 February, was figured and described,* but its actual relationship could 

 not then be ascertained. Since that period no less than five examples 

 have been examined, mostly procured from the 18th to the 20th of 

 March each year, one only having been found in the bottom-net off 

 Sarclet, Caithness, on the 14th January. Of the others one was 

 captured in the surface-net off the River Eden, one in the bottom-net at 

 Station IV., Forth, that is, along a line parallel to the shore between 

 Joppa and Gullane Ness, and two in the bottom-net at Station VIII., 

 Forth, east of the Bass. There is thus nothing very , diagnostic in regard 

 to environment — except that the majority have not been far from 

 estuaries ; while the post-larval season seems to range between January 

 and March, the latter, especially, being characteristic. 



This post-larval form is distinguished by its comparatively large size, 



* Seventh Annual Report, Fishery Board for Scotland, Part III., p. 263, PI. III., 

 figs. 5, 6, and 7. 



