1889.] on the Life-Mstory of a Marine Food-jisJi. 393 



rises from the eggs both of the sedentary and creeping animals on 

 the bottom to the surface — where they sport in the summer sun, 

 undergo certain changes, and again descend as they assume the form 

 of the adult. The pelagic young food-fishes — swimming freely in 

 the ocean — thus have a double chance at them — first in their very 

 early stage as they rise, and again in their larger and later condition 

 as they descend. The enormous numbers, countless variety, and 

 ever-changing nature of the small animals either directly or 

 indirectly constituting the food of these little fishes form an im- 

 portant feature in the economy of the sea. Such animal forms 

 comprise those long known in the British seas, besides others more 

 familiar to arctic voyagers, or to the sunny waters of the Medi- 

 terranean, for, with modern apparatus and persistent eiibrt (thanks 

 to the- enlightened views of the Government acting through the 

 Fishery Board), our knowledge is always extending. 



It is a remarkable fact that it is primarily to plants in inshore 

 waters that the abundance and variety of animals are in many respects 

 due, especially if estuaries also debouch in the neighbourhood. Thus 

 nowhere are the swarms of Sagittae, Appendicularians, Crustaceans, and 

 other forms of fish-food more conspicuous than in the midst of a sea 

 teeming with diatoms, Ehizosoleniee, and other algoid structures.* 

 These nourish many of the lower forms upon which the crustaceans 

 and other higher types feed, the latter asain falling a prey to the fishes. 

 Moreover, while the larger forms of the Copepods and other crustaceans, 

 for example, afiord suitable nourishment for the more advanced post- 

 larval fishes, the multitudes of larval crustaceans (XaupJii) are adapted 

 to the needs of the smallest larval food-fishes. Xuw this plant-life 

 is specially abundant in A^^ril and May, just when the larval and very 

 young post-larval fishes appear more abundantly in the inshore waters, 

 so that the cycle is nearly complete, viz. from the inorganic medium — 

 through microscopic plant and larval crustacean — to the post-larval fish. 

 I have mentioned the neighbourhood of an estuary as a prolific source 

 of food for young fishes, and I need only explain fui'ther by instancing 

 the case of mussel-beds, which for months pour countless myriads of 

 larval mussels into the adjoining sea, far beyond the needs of the area 

 as regards mussel-culture, and which form a favourite food of the little 

 fishes at all stages, but especially from an inch and a half to three 

 inches in length. These fishes feed on the young mussels as they 

 settle down on the sea-weeds, rocks, and zoophytes in August, after a 

 free-swimming larval existence. Like some of the forms indicated 

 above, mussels live to a considerable extent on microscopic plants and 

 various minute organisms contained in the mud of the estuaries and 

 other sites, so that a rich and favourite food, universally liked by fishes, 

 is the product of these uninviting flats. Moreover, in passing, it may 

 be remarked that, while everywhere preyed on by the food-fishes, it 



The fact that certain fishes feed on Infusoria has not been overlooked. 



