68 PROVISIONAL AID TO THE STUDY OF TASMANIAN MOLLUSCA. 



32. Hanley ... 



33. Frauenfield 



34. Menke ... 



35. Mueller ., 



36. All others 



Total 



3 



2 



2 



2 



63 



716 



CLASSES, FAMILIES AND GENEBA. 

 Descriptive Account of the Various Classes, Families 

 and grenera of molluscs inhabiting tasmania, 

 Systematically Arranged According to Tryon, 

 (" Structural and Systematic Conchology, 1884." 



NOTE.— The Roman numbers refer to the number of the family, anil the Arabic 

 nnmbers in brackets to the number of the species ; both arranged in consecutive 

 order in the systematic list. 



Class CEPHALOPODA. 



Cuttle Fish, Squids, Nautili, etc. 



Head large, separate from the body ; eyes large, lateral ; 

 ears developed ; mouth with two horny or shelly beak- 

 like jaws with fleshy lips, and surrounded by eight or 

 ten fleshy Arms or numerous tentacles, furnished with, 

 an entire or slit tube, used in locomotion, which is 

 usually directed backwards in swimming. 



SYNOPSIS OF FAMILIES. 



A. Order Dibranchiata. 



Animal breathing by a single pair of symmetrical branchise 

 or gills ; eyes sessile ; shell internal or none ; mandibles 

 horny; arms with suckers. 



Sub-Order Octopoda. 

 Arms, eight ; no shell, (the so-called shell of the argonaut is 

 the egg nest of the female.) 



Sessile 



Suckers slightly pedicelled; female having 

 two of the upper arms expanded 

 into broad webs, one of which 

 secretes an egg nest (nautiliform 

 shell.) 



■Family 

 Octopodidse 



Argonautida? 



