1878.] MR. R. COLLETT ON CERTAIN GOBIOID FISHES. 323 



the head, and equal to the snout, whilst, on the contrary, the eye of 

 L. albus is contained 5 times in the length of the head, and is 

 shorter than the length of the snout, is of little consequence, as in 

 fact both the original specimens of Parnell and those from the 

 Christiania Fjord have rather the proportions of length given by 

 Kessler. Although this author expressly remarks that he knows 

 the mature females, he must have overlooked (as well as Parnell) 

 the differences between these and the males, and in his description 

 (for instance, of the structure of the teeth) only have taken notice 

 of the latter. 



B. General Description. 



Before entering into a more detailed description of the species in 

 general, I will briefly point out some of the principal peculiarities 

 which separate the individuals in the different periods of life. From 

 this it will be seen that the difference in the sexes of the species in the 

 fully developed state is considerably greater than with any of our 

 northern species of the typical genus Gobius. 



Out of the spawning -season the males and the females (which at 

 this time only exist in the shape of young specimens) are exactly alike 

 in appearance, although they soon reach the size of the old ones. 

 The body is slender, the head pointed ; the jaws, in consequence, are 

 less oblique, and seem, therefore, to be shorter. The teeth are all 

 uniform, minute, and form a close single row. The caudal fin is 

 slightly emarginated, the second dorsal and the anal diminishing 

 behind. In this stage they are all typical L. stuwitzii. 



The nearly mature males, the milt of which is not yet quite ripe, 

 have the head considerably more thickened, and longer jaws ; besides 

 the minute teeth, there is become visible an outer row of cylindrical 

 teeth, yet not full-grown, but having reached a greater length than 

 the others. The posterior rays of the second dorsal and the anal 

 fins are still lower than the anterior ; the caudal is slightly emargi- 

 nated, or square. 



Fig. 2. 



Head of Latrunculus pellucidus, mature male, magnified. 



The mature males have an average total length (the caudal in- 

 cluded) of 42-43 minims, (a few have the milt ripe, with a total 

 length of 40 millims.), but reach a size of 50-5 1 milhms. The body 

 is plump ; the head thick and tumid ; the interorbital space broad ; 

 the cleft of the mouth wide, with fully developed teeth of only one 



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