GREY MULLETS. 



399 



body being covered with strongly keeled and striated scales; and by the first 

 dorsal fin being composed of a number of short spines, and continuing to the 

 second. The elevated lower jaw has a convex upper border, bearing a single 

 series of rather small compressed and triangular teeth. Of the habits of this 

 scarce fish nothing definite seems to be known ; although in the young state it 

 is found in company with floating jelly-fish. At a later period of its existence 

 it probably descends to a considerable depth during the day, and comes to the 

 surface only at night. It grows to a foot and a half in length. 



From the two preceding families the grey mullets, which con- 

 stitute the third family of the group under consideration, may be 

 distinguished by the total absence of a lateral line, the presence of only four stiff 

 spines in the first dorsal fin, and the limitation of the number of vertebrae in the 

 skeleton to twenty-four. The more or less elongate and somewhat compressed 

 body is covered with cycloid or slightly ctenoid scales of moderate size ; the cleft 



Grey Mullets. 



COMMON GREY MULLET (\ nat. size). 



of the mouth is small or medium ; the teeth are feeble or wanting ; the lateral eye 

 is of moderate size ; and the gill-opening wide. In some species there may be 

 a fatty lid to the eye. The grey mullets (Mugil), of which there is a very large 

 number of species, are distributed over all temperate and tropical coast-regions, 

 frequenting brackish-water estuaries, and in some cases ascending rivers for 

 considerable distances. Feeding chiefly upon, the animals and organic matter 

 found in sand and mud, these fishes have a special straining apparatus in the 

 pharynx for the purpose of preventing objects of too large size from entering 

 the stomach, or foreign substances getting into the gill-chamber. It will be 

 unnecessary to describe the structure of this apparatus here ; but it may be 

 mentioned that after triturating a mouthful of sand or mud between the 

 pharyngeal bones, in order to extract such nutriment as it may contain, the grey 

 mullets reject the mineral part of it. Another peculiarity is to be found in the 

 structure of the oesophagus and stomach, the former being lined with long thread- 

 like papillae, while the latter has its second portion furnished with muscular walls 

 like the gizzard of a bird, although it is not divided into two lateral halves. 



