176 OMMASTREPHES. 



ill the Oxford clay, Solenhofen (Liassie), and there is a tertiaiy 

 species. 



Ommastrephes illecehrosa was observed among the wharves at 

 Provincetown, Mass., during the month of July, engaged in 

 capturing and devouring the young mackerel, which were swim- 

 ming about in schools, and at that time were about four or five 

 inches long. In attacking the mackerel they would suddenly dart 

 backward among the fish, with the velocity of an arrow, and as 

 suddenly turn obliquely to the right or left and seize a fish, 

 which was almost instantly killed by a bite in the back of the 

 neck, with the sharp beaks. The bite was always made in the 

 same place, cutting out a triangular piece of flesh, and was deep 

 enough to penetrate to the spinal cord. The attacks were not 

 always successful, and were sometimes repeated a dozen times 

 before one of these active and waiy fishes could be caught. 

 Sometimes, after making several unsuccessful attempts, one of 

 the squids would suddenly drop to the bottom, and, resting upon 

 the sand, change its color to that of the sand so perfectly', as to 

 be almost invisible. In this way it would wait until the fishes 

 came back, and when they were swimming close to or over the 

 amlniscade, the squid, by a sudden dart, would be pretty sure to 

 secure a fish. Ordinarily, when swimming, they were thickly 

 spotted with red and brown, but when darting among the 

 mackerel, they appeared translucent and pale. The mackerel, 

 however, seemed to have learned that the shallow water is the 

 safest for them, and would hug the shore as closely as possible, 

 so that in pursuing them many of the squids became stranded, 

 and perished by hundreds, for when they once touch the shore, 

 they begin to pump water from their siphons with great energy, 

 and this usually forces them farther and farther up the beach. 

 At such times they usually discharge their ink in large quantities. 

 The attacks on the young mackerel were observed mostly at or 

 near high water, for at other times the mackerel were seldom 

 seen, though the squids were seen swimming about at all hours ; 

 and these attacks were observed both in the day and evening. 

 But it is probable, from A^arious observations, that this and the 

 other species of squids are partially nocturnal in their habits, 

 or at least are more active in the niaht than in the dav. Those 



