76 AllGONAUTA. 



himself to the surface of the sea by ejecting a 

 quantity of water, and thus diminishing the specific 

 gravity of his vessel. When floating in a calm, he 

 would throw out two or more tentacida, to serve 

 as oars. If a favouring breeze sprung up, he would 

 stretch a fine membranaceous sail on two extended 

 limbs, and, steering with his other arms, shew his 

 ready skill in naval tactics, by numberless evolutions 

 with his fragile bark. On the approach of danger 

 he would suddenly haul in his tackle, and, by a 

 rapid absorption of the water, betake himself to 

 the security of the fathomless abyss, his native 

 dwelling. On account of this talent of quickly 

 discerning and avoiding his pursuers, the saga- 

 cious little mariner is seldom taken in the act of 

 sailing, but is usually fished up upon rocky shores, 

 or entangled in the nets of fishermen at sea. 



One species, the rare and beautiful A. Fitreus, 

 has sometimes been placed among Patellse, but, 

 surely, with little judgment. It has, also, been 

 made to form a new genus, but without necessity, 

 for it answers correctly to the Linneean definition 

 of Aigonauta, and moreover possesses the promi- 

 nent characteristic, the dentate keel. 



