308 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [98] 



young mackerel were mostly 8 to 10 inches long, and some of them were 

 sfeill larger. 



This species, like the common Loligo, has the instincts and habits of 

 a cannibal, for small squids of its own species form one of the most com- 

 mon articles of its diet. From an adult female of ordinary size (G, of our 

 tables), caught at Eastport, Me., I took a great mass of fragments of 

 small squids, with which the stomach was greatly distended. These 

 fragments completely filled a vial having a capacity of four fluid ounces. 



From the rapidity with which the squids devour the fish that they 

 capture, it is evident that the jaws are the principal organs used, and 

 that the odontophore plays only a subordinate part in feeding. This is 

 confirmed by the condition of the food ordinarily found in the stomach, 

 for both the fishes and the shrimp are usually in fragments and shreds 

 of spme size, and smaller creatures, like Amphipods, are often found 

 entire, or nearly so ; even the vertebrae and other bones of herring are 

 often present. On the other hand, in some specimens, the contents of 

 the stomach are finely divided, as if the odontophore had been used for 

 that purpose. 



Notes on the visceral anatomy. 



Plate XIX, figure 1. Plate XX, figure 1. 



This species, in common with others of the same genus, is very differ- 

 ent from Loligo Pealei in the form and structure of many of its internal 

 organs. The branchial cavity is larger and the gills (g, g) originate farther 

 back and are much larger than in Loligo, their length being about two- 

 fifths the entire length of the body ; they originate back nearly at the 

 middle of the body. The liver (I, I) is much larger and more conspicu- 

 ous, consisting of two large, oblong, lateral lobes or masses, closely 

 united together in the median plane, with a groove along the dorsal side, 

 in which lies the oesophagus. The ink-bag {i) is elongated-pyriform, 

 with a silvery luster externally, but blackish when filled with the ink. 

 The size and form of the stomach and its coecal lobe (s, s') vary greatly 

 according to their degree of distention with food. When well filled 

 they are very large, saccular, and more or less pyriform, the coecal lobe 

 extending back nearly to the end of the body. The walls of the stomach 

 are in part thick, muscular, and longitudinally plicated within. The in- 

 testine (h) has two spatulate papillae, one on each side of the anal orifice. 



The heart (H) is large, somewhat irregular and un symmetrical, with 

 four points, the two lateral continuous with the afferent vessels (bo) of 

 the gills ; the anterior passing into the anterior aorta (ao) ; the poste- 

 rior median one, continuous with the posterior aorta, gives off first a 

 small ventral branch, which supplies the reproductive organs, and then, 

 later, a median ventral artery (o), going to the mantle; while much far- 

 ther back it divides into two branches (o', o'), which supply the sides of 

 the mantle and caudal fin. The branchial auricles [an) are large and 

 ovate, with a small, round capsule at the posterior end. 



The anterior urinary organs or 'kidneys' (r, r) are voluminous, deeply 



