OCR Text |
Show 1878.] MR. R. COLLETT ON CERTAIN GOBIOID FISHES. 323 the head, and, equal to the snout, whilst, on the contrary, the eye 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 emarginated, or square. Fig. 2. Head of Latrunculus pellucidus, mature male, magnified. The mature males have an average total length (the caudal included) of 42-43 millims. (a few have the milt ripe, with a total length of 40 millims.), but reach a size of 50-51 millims. 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 21* |