392 



Professor W. C. Mcintosh 



[Feb. 1, 



Fig. 11, 



young specimens present in addition a row of clear transverse bands 

 which subsequently disappear. 



The larval salmon enters the world of a size — though small — 

 that is readily recognisable, viz. about three-fourths of an inch in 

 length, but the marine forms under consideration, from their minute 

 size and glassy translucency, are almost invisible to the naked eye — 

 just a gleam of light broken by the passage of a different medium, 

 or a tinge of pigment, arresting attention. Only in the cat-fish 

 (which is not much — though it ought to be more — of a food-fish) 

 with its large egg, have we a size nearly reaching that of the salmon 

 at birth. 



We had left the larval fish tossed about by the currents and 

 unable to struggle against them, now floating with its yolk-sac 



uppermost, or hanging in the water with 

 its head downward, and again making 

 spasmodic darts hither and thither. Soon, 

 however, it gathers strength, and at the 

 end of a week or ten days it glides 

 actively through the water, and avoids 

 both obstacles and enemies, the young 

 cod nimbly escaping the forceps, poising 

 itself in the water with its large pectoral 

 fins (Fig. 11), and evincing both intelli- 

 gence and dexterity. Moreover, this 

 activity greatly promotes respiration in 

 those like the gurnard with a motionless 

 mandible, the water being thus sent 

 through the mouth and over the bran- 

 chial region. Its mouth has now opened 

 and the yolk-sac has been absorbed, while 

 it feeds on the most minute of the little Copepods, especially those 

 almost microscopic in size, that swarm in the surrounding water. 

 The provision whereby such little fishes find in the ocean food suited 

 to their capacities is one of the most striking features in nature, 

 but it has only recently been carefully investigated.* It is a notion 

 no longer tenable that during the winter and spring the sea — to a 

 large extent — is devoid of the wealth of pelagic life so characteristic 

 of the summer months — ^just as it is of the genial waters of the 

 tropics. For several years, however, it has been known that a vast 

 abtindance of minute life of all kinds is present throughout the 

 entire year — and from the surface to the bottom. Moreover, 

 during the warmer months a constant succession of young forms 



Anterior (ventral) region of 



larval Cod with great pectoral 



fins, magnified. 



* Vide La fanne pelag'que du Golfe de Marseille, par Gourret, Ann. du 

 Mnsee d'M=t. nat. de Marseille, II. 18S4. The pelagic fauna of our shores in 

 relation to the nourishment of the young food-fishes, Ann. Nut. Hist. Feb. 1887. 

 ALo Hensen and Mobius in tiinfter Bericht der Kommission zur wiss. &c. der 

 deutschen Meere. Berlin 1887, pp. 1 and 109. 



