308 THE SAND-EEL FAMILY. 



abundance, at once prompt us to ask the question — whence 

 come they ? 



They are practically post-larval, the yolk having in 

 most cases been absorbed (Plate XII, fig. 7), but they have 

 barely completed their larval period. We know that the 

 eggs are buried in the sand and therefore the quiet period 

 of larval existence during which the embryo absorbs its reserve 

 . of yolk-nourishment and prepares itself for active pursuit of its 

 prey is most probably also spent in or on the sand. The other 

 alternative seems to be that of supposing that the young 

 larvae, retarded by their yolk-sacs, wriggle out of the sand, 

 after hatching, and spend their larval period pelagically, or 

 upon the bottom : in either case some at least of them would 

 fall a prey to the surface- or bottom-nets, whereas such is not 

 the case. 



Some observers, quoted above, speak of the sand-eel as 

 spawning in the winter, and we have direct evidence that it 

 does so in the end of December and in January on the east 

 coast of Scotland. If we take into consideration the retarding 

 action of a low temperature the probabilities are that it is these 

 winter eggs that give rise to the swarms in March. 



If, as may be possible, the early larval period is spent in the 

 sand, then the sand-eel during its embryonic and larval stages 

 has a quiescent stage of development protected from its many 

 rapacious foes, which pursue it with remorseless energy during 

 all its future changes of habitat, till the greater number of the 

 adults again take refuge in the same shelter. In all probability, 

 however, it leaves the sand as soon as it is hatched. Moreover, 

 many have the intestine of a greenish hue, probably from algoid 

 substances. 



The March sand-eels are continually reinforced by fresh 

 consignments emerging from the sand, till the end of April, 

 but contemporaneously with this a migration of the larger ones 

 commences. At the average length of about 9 or 10 millimetres 

 (about ^ inch) the little fishes forsake the bottom, and are 

 now found in the mid-water, being doubtless led thence in the 

 pursuit of their food. The sand-eel has now the general 

 appearance seen in Plate XII, fig. 8. The figure was drawn 



