ARGONAUTID. 23 
is peculiar to the female: its special function is for the protection 
and incubation of the eggs. It is not homologous with the 
chambered or internal rudimental shells of other cephalopods, 
but may be compared with the cocoon of the leech, or the float 
of Ianthina. The Argonaut sits in its boat with its siphon turned 
towards the keel, and its sail-shaped (dorsal ) arms closely 
applied to the sides of the shell It swims by ejecting water 
from its funnel, and crawls in a reversed position, carrying its 
shell over its back like a snail. 
The male Argonauts (xvi, 84, 85), are one inch in length, and 
possess no shell; their dorsal arms are pointed, not expanded. 
The testis is large, and like that of the Octopus in structure and 
situation ; it contains spermatozoa of different degrees of devel- 
opment, and the excretory duct probably debouches into the 
hectocotylus. 
A living Argonaut was captured at Long Branch, New Jersey, 
by a fisherman, in August, 1876. It was kept alive for eight or 
nine days and made feeble attempts to swim in its narrow con- 
finement (Am. Nat.,xi,243). Numbers of fresh shells have been 
recently dredged, Rinoak 90 miles south of Narraganset Bay, 
R. I., by the U.S. Fish Commission. 
The occurrence of the Argonaut on the Florida coast, in one 
instance with the animal entire, is mentioned in Am. Nat., xii, 397. 
Dr. H. Muller observes that the female Argonaut appears 
periodically in great numbers at Messina during the spawning 
season, but at other times her usual habitat is at the bottom in 
deep waters. The male is always very small, and is rarely met 
with: its hectocotylized arm is det: ached during coition and is 
found in the mantle of the female, where it enjoys a prolonged 
separate life, although unprovided with digestive organs. The 
young female an inch in length, has no shell; it is developed 
later. 
In South Australia, at certain seasons of the year, during the 
prevalence of strong northerly winds, the shells “of the female 
Argonaut are washed ashore in considerable numbers. Many of 
these shells contain the animal in a living state; but they soon 
fall a prey to the sea-gulls, by whom they are greedily devoured. 
SuporvDErR II]. DE CAPODA. 
Body oblong, laterally finned; arms consisting of eight normal 
(sessile) ones, and two longer or tentacular arms, which are 
contractile or retractile; suckers provided with corneous rings, 
sometimes armed with teeth, or with hooks; shell dorsal, internal. 
One or two of the sessile arms are modified for copulation. 
