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Show 1878.] MR. R. COLLETT ON CERTAIN GOBIOID FISHES. 327 The mucous glands1, the true nature of which has perhaps not yet positively been proved, are to be found on all parts of the head in longer or shorter rows, which vary comparatively little in the different specimens. To give a more detailed description of them would require too much space ; but a drawing (see fig. 2, p. 323) has been taken from a comparison of several specimens. Two parallel series across the hinder part of the interorbiral space are easy to be observed, as may also two others, running along the upper side of the snout, and sending forth some shorter series down to the nostrils. The rest of these glands reach as far back as to the first dorsal fin ; and shorter rows are found immediately behind the ventrals. The scales and the skin.-The whole body, with the exception of the head and fins, as well as the neck, throat, and belly, down to the vent, is covered with large and very easily deciduous scales. These are fastened to transverse muscular impressions, which bend together in the lateral line of the body, where the vertebrae are connected. The scales are arranged along the sides of the body thus:-First a series of 25 scales are fixed along the lateral line; above and below this row run two other rows ; so that together there are 5 rows between the dorsal and ventral line. The scales are perfectly transparent, membranous and cycloid ; in the lateral line they are a trifle smaller than in the other rows ; they are comparatively large, having a diameter of nearly 1 millim., and are few in number. According to the above statement the total number of scales would be hardly more than 100 on each side of the body. The period in which the scales are developed I have not been able to observe to a certainty, as the scales in young specimens seem to be still more easily deciduous than in the older. In the smallest specimen I have found, with a total length of 13 millims., the transverse impressions, to which the scales are fastened, are already visible ; but I have not detected the scales themselves before the specimens have attained about half their size. The colour.-When alive the whole body is almost perfectly transparent, having only a few minute stellulate pricks in the skin. One may without difficulty count the vertebrae from the outside, and clearly distinguish the brain with its different parts, as well as the pulsation and the blood-corpuscles. The most coloured part of the body is the eye, and the innermost part of the black bladder. When preserved in spirits, or in a frozen state, they soon become white and opaque, whilst if preserved in glycerine they remain half transparent; then the minute pricks become fainter, whilst the iris always retains its silvery colour. In the breeding-season the minute pricks become more numerous, especially in the males. A row of these pricks, yellowish red in colour, stretches along the sides, corresponding in number to the vertebrse. Along the dorsal line another row of brown pricks is found. Along the anal fin, on each side of the root of the rays, is a row of black pricks, which continues behind the end of the fin in 1 "Stripes of minute warts," Gunther, Catal. vol. iii. 1861; "External papilla; of taste," Winther, Naturh. Tidsskr;3. R., 9. B., p. 181, Kbhvn. 1874. |
