WRASSES. 



419 



is more or less short and compressed ; there are weak teeth in the jaws but none 



on the palate, and there is an air-bladder. The family is represented by eight 



genera and considerably over a hundred species ; and the genera may be divided 



into groups, according as to whether all or some of the opercular bones are serrated 



at the edges or are all simple ; Pomacentrus belonging to the intermediate group, 



in which the preopercular is serrated, while the edges of the other bones of the 



gill-cover are entire. In a fossil state the family is represented by an extinct 



genus from the middle Eocene deposits of Monte Bolca. Pomacentrus is the 



largest genus of the family, its representatives ranging over the tropical seas 



of both hemispheres. Curiously enough, not only do these fishes resemble the 



scaly-finned fishes in their mode of life, but they are very similarly coloured, 



so much so, indeed, that in some instances actually the same pattern of coloration 



is common to members of the two families. This, as remarked by Dr. Giinther, 



is one of many instances showing that the coloration of animals depends to a 



great extent on their mode of life and natural surroundings. All these fishes 



are carnivorous, subsisting on various small marine animals ; those furnished 



with compressed teeth probably browsing on the coral-polyps. 



Distinguished from the preceding family by their cycloid scales, 



the wrasses form an extensive group (Labridce), many of the members 



of which may be easily recognised by their greatly thickened lips, sometimes 



provided with an internal fold ; and from this character they derive their German 



title of lip-fishes. False gills are present, and the true gills, three and a half in 



number on each side. The body is oblong or elongate, and while teeth are present 



in the jaws they are absent on the palate. In the single dorsal fin the number 



of spines is usually equal to that of the rays ; the anal is similar to the soft dorsal, 



and an air-bladder is present. Littoral in their habits, the great majority of the 



wrasses are found in tropical and temperate seas, none occurring within the limits 



of the polar seas. Rocks and coral-reefs are their favourite haunts, most of them 



feeding chiefly on molluscs and crustaceans, for crushing the shells of which their 



teeth are specially adapted. In many kinds there is an additional pointed curved 



tooth at each angle of the upper jaw, used for holding a shell against the front 



and side teeth, by which it is crushed. The majority of the wrasses are beautifully 



■coloured fishes, decorated not only with transient iridescent hues on the scales, 



but likewise with permanent colours formed by the deposition of pigment in the 



tissues. Some of the species grow to a large size, specimens weighing upwards 



of 50 lbs. ; and it is these larger species which are most esteemed as food-fishes, 



the flesh of the smaller kinds being of inferior quality. In a fossil state wrasses 



date from the middle Eocene of Monte Bolca, where remains referable to the 



existing genus Labrus occur ; while an extinct Eocene genus from North America 



appears to be the ancestral form of the existing black fish (Tautoga). An allied 



extinct family is represented by Phyllodus, from the Cretaceous and lower Eocene 



of Europe — distinguished by the flattened leaf-like pharyngeal teeth — as well as 



by several other more or less nearly related Tertiary types. 



As it would be quite impossible in our limited space to describe 

 True Wrasses. . » ,, P 



even a tew or the numerous genera of wrasses, we must content 



ourselves with saying that these are arranged in groups according to the structure 



