12 



THE SHELL-FISH OF THE COAST. 



A form of squid very similar to the one just de- 

 scribed, and largely replacing it in the northern 

 waters, is the Ommastrephes 

 sagittatus^ in which the ten- 

 tacular arms are of compara- 

 tively short length, and the 

 cornea of the eye perforated, 

 so as to permit of the entry 

 of sea-water to the lens. 

 While rare with us, this 

 animal sometimes appears 

 in the northern waters in 

 immense shoals, following 

 in the wake of the mackerel, 

 which constitutes its selected 

 food. In this condition it 

 does not hesitate to enter the 

 pounds and weirs, or to nav- 

 igate between the piles of 

 wharves, darting with the 

 swiftness of an arrow into 

 the midst of its prey, and 

 pouncing upon the neck of 

 a selected victim. In this 

 pursuit of the mackerel the 

 squid may be observed to 

 change color frequently, adapting itself in tone, 

 by an intuitive manipulation of the pigment-bodies 

 (chromatophores), to the surroundings which it 

 traverses. The squid, like many other cuttle- 

 fishes, is in a measure nocturnal in its habits, and 

 is thought to be fond of gazing at the moon. 



OMMASTBEFHES 3AGITTATU3. 



