BY JAMES C. COX, M.D., F.L.S., ETC. 777 



always make this work the basis on which dissertations on this 

 class must depend. 



In the present paper I intend to confine my observations to 

 the Octopodidoe, and principally .to those species found frequenting 

 the coasts of this part of the southern hemisphere, leaving- the 

 Decapoda for future consideration. 



Class CEPHALOPODA. 



Head large, distinct from the body : eyes complex, fixed or 

 moveable : mouth with a pair of mandibles or beaks, acting 

 vertically, like those of a parrot, edged with fleshy lips, and 

 surrounded by a circle of arms. The sexes are always distinct. 

 and in habits all are marine and predatory, existing on shell-fish, 

 crabs, and fishes. 



Order 1. Dibranchiata, (Owen), Octopods, Argonauts, Cuttle-fish, 

 squids, &c, &c. 



Breathing by a single pair of internal symmetrical, plume-like 

 branchiae, or gills. Animal swimming, naked"''': eyes sessile, 

 prominent : mandibles horny : arms eight or ten. provided with 

 rows of acetabula, suckers, or cups : body round or elongated, 

 frequently laterally or posteriorly finned : shell internal, horny 

 or shelly, or none : ink gland always present. 



Order 2. TetrabrancMata, (Owen), Nautili, Ammonites, &., &c. 



Breathing by two pairs of internal symmetrical, plume-like 

 branchiae, or gills. Animal creeping, protected by an external 

 shell : eyes pedunculated : mandibles calcareous ; arms, or rather 

 tentacles, very numerous, not furnished with acetabula, or suckers: 

 body attacked to the shell : siphon an incomplete tube formed 

 by the union of two lobes : shell external, many chambered, 

 outer layer porcellanous, inner layer and partitions nacreous ; 

 body chamber capacious in which the animal lives ; no ink gland. 



*The external shell of the Argonaut is simply the egg- nest of the female. 



