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



kind, few in number, but long and cylindrical. The posterior rays 

 of the anal and second dorsal fins are, as a rule, not shorter than the 

 anterior, making the fins about even in their whole length. The caudal 

 fin is slightly square, with rounded edges in the young individuals, 

 but truncated in the elder ones. 



The nearhj mature females, not yet quite ready for spawning, 

 agree in general with the individuals in the immature state, from 

 which they differ in the somewhat swollen belly. 



The females ready for spawning have an average length of about 42 

 millims. ; many having the spawn ripe are of a length of 38 millims. ; 

 none reach a length of more than 46 millims. (the caudal included). 

 The head is not visibly thickened, but is about the same as during the 

 whole young period ; it is rather more pointed than in the male ; 

 the cleft of the mouth is considerably smaller, although the jaws 

 may possibly have become a trifle longer than before. The teeth, 

 however, have not undergone any change, but are uniform, exceed- 

 ingly fine, and placed in the same row as in the young individuals. 

 The caudal fin is emarginated, and the anal and the second dorsal 

 are tapering behind, as is the case in their younger state. 



The construction of the body is slender and elongated, laterally 

 compressed ; and it is only during the spawning-season that the body 

 of the male becomes thicker and more plump. 



A specimen of medium size out of the spawning-season has a 

 total length of 40 millims., of which the head is 9 millims. ; and this 

 is contained about 4'4 in the total length (the caudal fin included). 

 The greatest height is 5"5 millims., or contained 7'2 in the total. 

 The vent is situated about 2 orbital diameters nearer the snout than 

 the root of the caudal. 



In the spawning-season the body becomes fully developed, 

 although the total length does not increase. In a male with a 

 total length of 40 millims. the length of the head is 9"5 millims. 

 (4*2 in the total) ; in the female about the same as before. 



The eyes have a diameter of 2 millims., and occupy |- of the 

 length of the head. The orbital space, which, as a rule, is narrow,' 

 and does not reach the breadth of an orbital diameter, has in the 

 mature male fully the last-named breadth. 



The number of the gill-rays is 5 ; the gill-openings are wide, and 

 stretch forwards to about the middle of the orbit. 



The mouth is oblique, and the lower jaw longer than the upper, 

 the maxillary extending to below the middle of the orbit. During 

 the spawning-season the jaws of the male become considerably 

 larger and more oblique ; at the same time, the head and all parts 

 of the body become swollen, the jaws extending much deeper under 

 the eye. 



The number of the vertebrae is 27 ; the processus spinosi are very 

 long, and reach almost to the dorsal and ventral line. The medulla 

 spinalis extends as far back as to the middle of the 22nd vertebra. 



The teeth. — Before the spawning- season the structure of the teeth 

 is exactly alike in both sexes. In each of the jaws is found on 

 both sides a single series of 20-25 minute and very closely fitted 



