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 tentacula, 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. Vitreus, 
has sometimes been placed among Patellae, but, 
surely, with little judgment. It has, also, been 
made to form a new genus, but without necessity, 
for it answers correctly to the Linnaean definition 
of Argonauta, and moreover possesses the promi- 
nent characteristic, the dentate keel. 
