Phyllopoda of Australia. 251 



2, pp. 1-17, pis. 1-4. Spencer and Hall, Repoi't Horn Expedi- 

 tion, Zoology, ii., p. 236, figs. 9-14. 



Synonym 1 E. boysii, Baird. 



Specific Characters. — Shell tumid, seen from the side ovoidal, 

 vaiying somewhat in shape, of firm consistency. Umbones well 

 defined, occuring much nearer anterior than posterior end. 

 Ridges numerous, vaiying in number in diiTerent varieties. 

 Sculpture between ridges formed by more or less radiating lines. 

 Dorsal tail-plates thickly fringed with small acute denticles. 

 Segments of trunk dorsally with many spines. Distal dorsal 

 limit of head always distinctly produced backwards as a lappet 

 to overlie the following cervical segment. Scarcely swollen in 

 front of eyes. 



Distribution. — Lake Bonney, near River Murray, and Fowler's 

 Bay, both in southern area of South Australia (Brady, typical 

 variety). Common in waterholes along the Finke and its tribu- 

 taries, also in the Macumba and Stevenson Rivers, Central 

 Australia (S. and H., three varieties) ; Hay, N. S. Wales (Sars, 

 typical variety). Typical variety common in many places in 

 Northern and Southern Victoria ; and if Sars is right in thinking 

 E. boysii specifically identical, also India. 



The following four varieties have been determined by Spencer 

 and Hall : — 



Estheria packardi., var. typica. 



Length of adult shell about 9 mm. Spirit specimens dark 

 brown. Ridges, about 24 ; sculpture, well defined radial straight 

 lines, with their inner ends branching. 



Estheria packardi, var. cancellata. 



Shell more tumid than the preceding variety, but about similar 

 in size. Ridges, 30-40, crowded towards the margin ; sculpture 

 strongly marked, towards the margin with the crowded I'idges 

 cancellated, and their inner edge moniliform. 



Estheria packardi., var. minor. 



Shell moderately tumid, smaller than above (about 4 mm.). 

 Dorsum declining posteriorly behind the umbones. Umbones 

 very prominent. Ridges very numerous (about 30), beset with 



