338 MR. R. COLLETT ON CERTAIN GOBIOID FISHES. [Mar. 5, 



few materials at my disposal. In all probability Cryst. nilssonii reaches 

 (as is the case with Latr. pellucidus) maturity at the age of one 

 year, after which it disappears. The spawning-season is probably 

 the same as in the other species, consequently during the summer 

 months ; on the whole, however, it appears to have a somewhat 

 longer duration. 



From the researches I have been able to make among col- 

 lected specimens, compared with those preserved in the Museum 

 of the University, it appears that the spawning probably begins in 

 some individuals as early as in March or April ; perhaps the greater 

 number attain their maturity in the last part of June ; whilst in other 

 specimens the spawning does not take place before the beginning of 

 August, or perhaps later. After the conclusion of the spawning the 

 specimens no doubt perish, their life having thus lasted only one 

 year. 



Habits. — In its habits this fish probably agrees perfectly with 

 Latr. pellucidus. The extraordinarily compressed body denotes that 

 it swims freely about in rather deep water, and not, like most of the 

 true Gobii, resting itself at the bottom ; in fact this would be almost 

 impossible, on account of the peculiar construction of the ventrals of 

 the male, and, in the case of the female, from its entire want of these 

 fins. Most of the specimens mentioned by other authors have been 

 taken in the dredge at a depth of 30 fathoms. Von Diiben and 

 Koren state that some of their specimens crept into empty tubes of 

 Chcetopterus norvegicus, in which, however, they had only taken 

 refuge whilst the dredging was going on. 



In the Christiania Fjord I have taken these fishes, together with 

 Latr. pellucidus in nets set out for mackerel, Clupea sprattus, and 

 young of 01. harengus. The nets bring them to the surface in the 

 same manner as is the case with L. pellucidus. Asa rule they lose 

 the capability of again descending, from the swimming-bladder 

 becoming strongly distended when they reach the upper strata of the 

 water. This fish is met with in far less numbers than the last-named 

 species. In the same manner it is taken as food by other fishes ; 

 and I have taken it from the stomach of small young examples of 

 Gadus morrhua. 



Food. — Upon examining a number of stomachs of individuals 

 taken in the month of June, I have found them filled with digested 

 remains of Entomostraca, without, however, being able to recognize 

 any species of them. Probably they were Calanidse, or, perhaps, 

 pelagic Copepoda of the same species as are found in Latr. pellu- 

 cidus. 



Distribution. — Besides being found in Norway, Cr. nilssonii has 

 been taken more lately on the coast of Bohuslen (Sweden) ; and 

 perhaps it also occurs on other parts of the coast of Northern Europe. 

 In Norway its habitat extends from the Christiania Fjord along 

 the western coast, nearly to the Trondhjems Fjord, in about 63° N. 

 latitude. 



The most northern point at which it has been found was at Chris- 

 tiansund, in July 1843, by v. Diiben, and also about the same 



