140 
Type. Australian Museum. 
Shell globosely conoid, whorls rounded, spire elevated, base 
rounded, aperture subcircular, umbilicus narrow. Diam. maj. 8, 
min. 7, alt. 6, mill. 
Hob. The western flanks of Mount Ledgbird. 
The two latter forms are considered by Mr. Brazier to be species, 
an opinion from which I differ with much reluctance. 
13. Placostylus ijivaricorus, CJaskoin r 1854. 
Illustrations . Gaskoin, P.Z.S., 1854, pi. 29, tigs. 4, 5; Gassies, 
Faune conchyliologique de la Nouvelle Caledonie. pi. 3, fig. 2. 
Descriptions. Gaskoin, P.Z.S., 1854, p. 152; Gassies, Faune 
conch, de N. Cal., p. 47 ; Pfr., Mon. Hel. Viv., Yol. iv., p. 447 ; 
Crosse, Journ. de Conch. 1864, p. 128; Brazier, Aust. Mus. 
Mem. 2, p. 27. 
Type . British Museum (?) 
Hah. All over the island in sheltered places under stones; 
abundant. 
The auriculoid Bulimi form so natural a group, limited in geo- 
graphical range, bearing a most characteristic shell and sharply 
defined by its dentition from the typical Bulimi that it appears 
more convenient to accord Placostylus specific rank than to reduce 
it as in Fischer's Manual to a section of Bulimulus. This species 
speaks eloquently of a recent land connection extending on the 
one side to New Caledonia and on the other to New Zealand. It 
is confined to Lord Howe Island and, the Loyalty Island habitat 
quoted by Crosse is erroneous. This shell is as variable as any 
of its polymorphic genus ; were the extreme forms only available 
for study, two recent and another extinct species would be recog- 
nised by all schools of conchologists. 
Jaw (pi. xxi., fig. 4) folded, kidney-shaped, thin, membranous, 
margins recurved, ends angled, folds asymmetrical, about 14 on 
each side, oblique, enclosing a triangular median space, scarcely 
denticulating either margin. Radula (pi. xxii., fig 3) tongue shaped 
three times as long as broad ; formula, 127 rows of 35 : 22 : 1 : 22 
: 35 ; rachidian furnished with a slender median lance cusp whose 
cutting point projects beyond the basal plate, half way along the 
reflection are seated two small auxiliary cusps ; the lateral main 
cusp is ovate, stouter and blunter than that of the rachidian and 
also surpasses the posterior margin of the basal plate, the inner 
auxiliary cusp is suppressed and the outer increased, the alate 
margin of the basal plate is almost falcate ; the laterals pass 
gradually into the marginals whose main cusp diminishes and 
becomes double headed. 
These observations agree with those of Fischer on P porphy- 
rostomus and P . scarabus , Journ. de Conch., 1871, Yol. xix., pp. 
