of Spirula australis, Lamarck. 5 
punctate pigment is continued a little way on the inner surface 
of the mantle. 
The eight ordinary arms (of which the four of the left side are 
shown in PI. I. figs. 1, 4) are of nearly equal length, the first 
and fourth being the shortest, the third the longest; they are 
joined together by a short and thick web, or duplicature of the 
skin, at the outer side of their basal interspaces (PI. I. fig. 5). 
Compared with the others, the bases of the two ventral arms 
(4, 4) are the thickest, and the division between them is 
deepest and widest. Each of the arms is conical and trihedral 
with the long angle outward, and one face turned inward. 
This surface is bounded by a well-defined border on each side 
(fig. 6,?), and is beset with numerous, minute, pedunculate ace- 
tabula, thick-set at the distal half and arranged in an irregular 
quincuncial order ; five or six may be counted in the oblique 
rows that cross the surface. The acetabula (figs. 6, a, b , c) 
are oblate spheroids or pear-shaped, more flattened at the side 
upon which the small suctorial cavity (ib. s) opens, with 
slender peduncles (ib. p) equalling the acetabulum in length 
and inserted toward one side of the end next the arm. On 
some of the arms there were one, two, or three longer pedun¬ 
cles with larger acetabula than the rest, formed by the swelling 
out of one side of the sucker into a spheroidal tumour, con¬ 
taining a compact light-brown substance. The margin of 
each cup is strengthened and armed by a delicate iridescent 
horny hoop. 
The stems of the tentacles (figs. 1, 5, d*) equal in thickness 
at their base (fig. 5, d, d) those of the ordinary arms ; they are 
cylindrical, gradually contract to their terminal expansion, the 
inner side of which shows a narrow longitudinal raised tract, 
which supports the stems of the acetabula in a double alternate 
series. The corresponding part of the tentacles of Loligopsis 
Veranii offers a resemblance to this structure. 
The length of the oral mass (PI. I. fig. 8, magn.) is 5 millims.: 
it is connected with the surround ing cephalic sheath by loose, 
elastic, cellular tissue, yielding readily to the protrusive and 
retractile movements of the mass. 
Both mandibles (ib. figs. 8, 9, y>, q) were of horny or cliiti- 
nous tissue, of a dark brown hue, deepening to the free points, 
paling towards the thin inserted margins. There was no trace 
of calcareous superaddition. 
The beak is surrounded by a double lip — the inner one (figs. 
7 & 11, n ; fig. 11 “) thin, finely plicated, with a crenate border ; 
the outer one (fig. 7, 0 ) thicker, with coarse radiating folds on its 
inner side, the termination of which gives the border a crenate 
“ Proboscides Arist. 
