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



the shape of a short black stripe ; this is the most conspicuous and 

 durable of all the rows, and is never wanting. The caudal fin has 

 a brownish shade ; sometimes this is also the case with the anal fin, 

 whilst all the other fins are hyaline. The iris is silver-coloured, 

 with black pupil ; the upper margin of the eye is golden, which, 

 after death, changes to a black. The younger individuals are more 

 sparingly pricked; the row along the anal fin is the first which 

 shows itself, and is already visible in the young ones, with a total 

 length of 13 millims., where all the other pricks are wanting. 



In the males in full breeding almost, every part of the body has a 

 faint brownish light, although this is nowhere collected into larger 

 dots, but is most distinct along the transverse impressions of the 

 muscles. 



C. Habits and Distribution. 



Generation. — It is probable that no specimen lives more than one 

 year, and after tbe close of the breeding-time dies without living 

 through another spawning; consequently these fishes are really 

 annual vertebrates. 



The spawning-season occurs in the Christiauia Fjord in the summer 

 months. The latest date at which I have found females with 

 ripe spawn was on August 2, 18/2, although the greater number of 

 them had then already spawned. The normal period of spawning 

 is the end of June or the begiuning of July. On the 10th and 14th 

 of August, 1875, I found them in the middle of their breeding, 

 although several were still not quite mature. When the spawning is 

 finished all the specimens disappear entirely, and become apparently 

 extinct. 



The first young ones I took on August 28, 1875, when their 

 average size was 22 millims. ; a few specimens were rather larger 

 (attaining about 30 millims.), or less (down to 13 millims.). At the 

 same time there is not a single specimen of a greater size to be found 

 at those places where they, in the middle of June, were found iu 

 numbers and only in a full-grown state. 



A month later the median length may be estimated at 34 millims., 

 in the end of October at 38 millims. The development proceeds 

 tolerably even with them all ; and specimens are very rarely to be 

 found which differ to any degree from the medium size. Most of the 

 individuals attain their full size as early as December or January, in 

 order that, when the organs of generation begin to develop themselves 

 in the following spring, they may acquire greater plumpness and 

 strength in all parts of the body — a change which, as we have indicated 

 above, chiefly takes place in the males. Amongst the thousands of 

 specimens which I have examined during the autumn and winter, 

 1 have not found a single specimen with the slightest trace of tbe 

 long teeth that characterize the mature male ; and during the summer 

 time all the males, without exception obtain these teeth. 



In the young females, at the age of only four months, the ovaries 

 may be seen through the transparent body in the form of two elon- 

 gated strings, filled with clear eggs ; in the spawning-season these 



