250 On the Scales of Fishes. 



edge than to the root, is large, and covered with apparent 

 orifices, which do not penetrate through the scale; and toward 

 the free edge there are numerous lines or ridges, which come 

 from the disk, each of them being joined to the next by a cross 

 line in regular order. This series of lines ends abruptly at 

 each border of the scale, where it is narrower than in the 

 middle, and from this ending begins a series of fine lines, which 

 encircle the disk, from which portion of these lines the perfo- 

 rations are continued in the same manner as on the disk itself. 

 From the disk again there passes toward its root a large 

 number of diverging lines, of which some are divided in their 

 progress, and each of them is separated from the next by a 

 narrow channel; but such of these diverging lines as are nearest 

 the lines of the border which encircle the disk, end as they 

 approach to them. On all the scales of this fish that came 

 under observation there were apparent marks of the suspension 

 of growth and its renewal ; and, in one instance, the disk ap- 

 peared to extend over the whole breadth of the scale. A large 

 number of fine circular lines, of which about fifty were counted, 

 pass round the disk, and are also marked on or across the 

 diverging lines, or sections, that are carried to the covered 

 root. When fresh from the fish these scales were observed to 

 be smeared or lined with a silvery pigment. The description 

 now given at some length of the scales of the Scicena will apply 

 in its principal character to those of a large number of fishes 

 of somewhat similar shape, with the addition that in several of 

 them, as the river perch, the raised lines or minute ridges 

 which pass from the disk to the free edge, are carried still 

 further forward, so as to form a serrated border, which consti- 

 tutes a rough surface over the otherwise smooth skin. Such is 

 minutely the case in the comber, Serranus cabrilla ; the 

 common sea-bream, Pagellus centrodontus ; surmullet, Mullus 

 surmuletus ; piper, Trigla piper ; conspicuously in the top-knot, 

 Rhombus hirtus, where the border of the scale is turned 

 outward ; but this spicular arrangement is so minute in some 

 species, as the shad, Clupeidce, that its existence might be 

 questioned. The object of it seems to be to afford an additional 

 bond of security to the scale, for the skin is found to pass over 

 these projecting points. 



The disk which is thus the centre of extension in growth 

 is not always exactly at the middle of the scale, as ifc is 

 in the old wife, Cantharus griseus, where it reaches across its 

 extent ; and the scad, Garanx trachurus, top- knot, saury, 

 Scomberesiox saurus, and many others ; especially including 

 the whole of the cod-fish tribe, the hake ; but in many 

 cases, as the perch and sea-bream, the disk is much nearer the 

 free edge, in which case the growth towards the more concealed 



