OF NEW SOUTH WALES 61 



in use arming the tongue comprises about 24 rows." Mr. Wood- 

 ward subdivides the family into 9 genera, viz. : — Littorina, 

 Solarium, PJiorus, Lacuna, Litiopa, Rissoa, Skenea, Truncatella and 

 Lithoglyphus. This is not a natural arrangement for many reasons 

 which cannot be entered into here. He arranges the following 

 as subgenera under Littorina : — 



1. — Tectaria, Cuvier, 1827.* 

 Shell muricated or granulated, sometimes with an umbilical 

 fissure ; operculum with a broad membranous border. 



2.— Modulus, Graij, 1840. 

 Shell trochiform or naticoid ; porcellanous ; columella per- 

 forated, inner lip worn or toothed ; operculum horny or few 

 whorled. 



3. — FossARUS, Philippi, 1841. 

 Shell perforated, inner lip thin, operculum not spiral. 



4. — RiSELLA, Gray, 1840. 



Shell trochiform with a flat or convex base ; whorls keeled ; 

 aperture rhombic, dark or variegated ; operculum pauci-spiral, 

 5. — CoNRADiA, Adams, and Couthotia, Adams. 



The two latter from small species in the Japanese seas which it 

 is not necessary to refer to now. 



This arrangement is nearly that of Adams Brothers, in their 

 genera of Mollusca, only that the subgenera are suppressed and 

 the genera are placed as subgenera with Swainson's Echinella 

 and Adams' Isapis excluded. Chenu, in his " Manual," follows 

 the arrangement of Adams, but appears from the figures given 

 to confound one genus with another, supposing him to accept 

 the divisions given in the " Genera of Shells." 



I do not pretend to pronounce an opinion upon some of these 

 genera. I confine my attention in the first instance to those 

 which have reference to species existing on the Australian coast. 

 And first with reference to the genus Bisella. The history of 

 the genus has already been given by me in vol. I, p. 242, of the 



' There is a dispute about the priority of this name. Valenciennes is quoted by Adams, 

 but his name was Tectarius, and Montfort's Tectus. 



