158 



The Distribution of Crystallogobius Nilssonii. 



By 



J. T. Cuuninghaiu, M.A. 



When trawling with a small beam trawl on July 9tli last, a 

 couple of miles north of the Eddystone, I obtained a large number 

 of specimens of a fish which was quite unfamiliar to me. I found it 

 was Crystallogobius Nilssonii. The chief characters distinguishing 

 the species are the presence of only two rays in the anterior dorsal 

 fin of the male, and the almost complete absence of this fin and of 

 the pelvic fins in the female. The adult male is 4*4 cm. long, the 

 female about 3 cm. When alive the fish is very translucent, and it 

 is entirely destitute of scales. The species was first described by 

 Diiben and Koren in 1844 from half a dozen specimens taken near 

 Bergen. Robert Collett has well described it in the Proceedings 

 of the Zoological Society for 1878, having taken twenty-eight speci- 

 mens at about 30 fathoms in the Christiania Fjord in the years 

 1875 — 1877. Only forty-five specimens altogether had been taken 

 off the south and west coast of Norway at the time when Collett wrote. 

 I captured 201 specimens in a single haul of the trawl, 188 of which 

 were female and 13 male. Nearly all were adult, the eggs being- 

 visible through the integuments in the female. A few not quite full 

 grown are included among the 188 reckoned as female, and some 

 of these may prove on closer examination to be young males. In 

 any case the excess of females is very great. 



The species has already been included in the British fauna by 

 Day, a single specimen having been taken by Edward in a rock 

 pool at Banff. After I had identified my specimens, I received a 

 copy of a paper by Mr. E. W. L. Holt (Proc. Roy. Dublin Soc, 

 February, 1891), announcing that he obtained many specimens of 

 the same species in Ballinskelligs Bay at a depth of 30 fathoms on 

 the 21st August, 1890. It is evident, therefore, that the species, 

 hitherto supposed to belong chiefly to Scandinavia, is common 

 enough in certain localities on the British and Irish coast. The 

 depth where my specimens were obtained was about 28 fathoms, the 

 bottom, sand. The shrimp-trawl I was using was lined with 

 mosquito-netting for the express purpose of catching small and young 

 fish. 



