301 
BRANCHIATA, which includes nearly all the Bivalves, is 
‘said to number in all, Recent and Fossil, 14,000 species, and as 
it is calculated that there are quite 2000 species of existing 
species of this Class, it is evident that they must be proportionally 
exceedingly numerous in Australia. Almost all the Families 
are represented, those most conspicuously so being the 
Prctinipg#z, AvicuLipz, Myritip#, Arcip# (including 
the Australian genus T'rigonia), UNionipm, TELLINIDA, 
SeLENIDA, and Macrripm. Of the Class PTEROPODA 
nearly every Family is represented, but there are not more 
than 15 Australian species known in all. The Class GASTRO- 
PODA, everywhere numerous, quite keeps up its character in 
that respect in Australia. The Order SCAPHOPODA 
is represented by 15 species of the Dunratipm. The 
Order OPISTHOBRANCHIA is well represented. Of 
the Section ABRANcHIA there are six species. Of the 
Nupisrancuia 125 species, of all the families. Of the INFERo- 
BRANCHIA three species of Plyllidia ; and of the TECTOBRANCHIA 
about 50 species, belonging to all the families. Of the next 
Order of the Gastropods, the PPOROBRANCHIA, there are 
little short of 1500 species in Australia against a total of 12,000. * 
All the Families are to be found in Australia, but some in more 
than average abundance. The VoLutTip® alone number 200 
species, and Australia is considered the metropolis of the genus 
VoLuTa; the Cyprinipm, Conrpm, TEREBRID®, and 
Mouricip# are also very numerous. <A_ species of the 
Lirrorinip# of the genus Raulinia is found alive in New 
South Wales, while another species of the same genus is found 
fossil in the Paris Basin. The last Order of the Gastropods, 
the PULMENIFERA, are sufficiently numerous, but only two 
of the five families are included in the Australian Fauna,—the 
AURICULIDA, of which there are about 100 species, and the 
HeLicip#, numbering in Australia nearly 400 species. 
Australia is regarded as the true home of the genus Helix. Of 
the small class of HETEROPODA, few in number everywhere, 
there are in all eight Australian species, belonging to the genera 
Janthina and Reclusia. 
The CEPHALOPODA are abundant on the Australian 
Coasts. There are two species of Nautilus, one of Spirula, 
four of Sepia, two of Sepiola, ten of the Loliginide, three of 
Octopus, and three of the Argonautide. The Class 
TUNICATA are apparently very numerous, the AscrDIOIDIA 
particularly, but they have never been much studied, and really 
very little is known about them. Of the BIPHORA there 
are four species of the Salpide. 
The third Sub-kingdom of the Animalia, the A RT H R O- 
P ODA is, as in all parts of the world, exceedingly numerous 
