374 NOTKS ON EXPERIMENTS RELATING TO THE 



provided it be soft. Mr. Bateson fed his young specimens on minced 

 worm ; the adults will also eat worms, chopped Pectens, roe or milt 

 of herring and pilchard. In fact, they nibble at almost any kind of 

 soft food, but never swallow large pieces greedily, as many species 

 of fish do. 



Our mullet are also occasionally seen to take up a little of the gravel 

 at the bottom of the tank, and eject it again from the mouth. 



It is well known that grey mullet are usually found in the neigh- 

 bourhood of docks, piles, piers, harbours, &c., and that they ascend 

 estuaries. It is probable that they always live close to the shore, 

 and never go into deep water far from land. Considering this 

 natural habit and the mode of feeding observed in our tanks, it may 

 reasonably be inferred that this species feeds largely on Diatoms 

 and other lowly organised Algee, which always form a coating over 

 the surface of submerged masonry, wood, or iron, and over rocks. 

 It is interesting to note that the structure of the fish is peculiarly 

 adapted for such a mode of feeding. In the first place, the jaws, 

 instead of projecting to a point as they do in predatory fishes, are 

 extremely blunt, so that the lips form almost a straight line trans- 

 verse to the axis of the body. This form of the mouth, as in the 

 muzzle of herbivorous ruminants, is especially adapted for browsing 

 on vegetable growths covering a flat, hard surface. Secondly, there 

 are no teeth in the jaws ; the edge of the lower jaw is sharp and 

 straight, while the upper lip forms a thick elastic pad against which 

 the lower jaw can bite. This arrangement reminds one of the jaws 

 of a ruminating animal, such as a sheep or an ox, in which the 

 cutting edge formed by the incisors of the lower jaw bites against 

 the hard toothless pad formed by the gum of the upper jaw. 



But these and other peculiarities in the structure of the grey 

 mullet are not exclusively adapted to feeding off hard surfaces. 

 Dr. Giiuther states that the fishes of this genus feed on organic 

 substances which are mixed up with the sand or mud. Day mentions 

 that they are observed in an aquarium to suck in the sand, the 

 coarser portion of which they again eject. They are frequently seen 

 to do this in our tanks, but they never feed industriously in this way 

 as they do off the surface of the rocks and sides of the tanks. Day 

 also mentions that various minute molluscs, both bivalves and Gastero- 

 puds, small Crustacea, and fragments of Zostera and Conferva3, have 

 been found in mullets' stomachs. 



It is evident, therefore, that, unlike most marine fishes, the grey 

 mullet lives largely, though not exclusively, on plants, and particu- 

 larly on the lowest forms of Algse, especially the Diatomaceae. The 

 internal organs of these fishes, which differ so much from those of 

 the majority of fishes, and resemble in many respects those of grami- 



