of the girdle. On parting the vah’es a feature is at once discoA’ered
in the posterior one wiiich enables us to distinguish the species :
in this the margin is very much thickened within, of a dark brown
colour, smooth, flattened, and destitute of teeth, whilst in C. spiniger
the latter are strongly developed and coarsely striated. The colour
of the interior also differs : C. incanus is stained with dark brown,
the centre of the valves exhibiting a large defined hlack-hrown mark
over the jugal sinus, the laminae of insertion being whitish. The
central valves have a single, very small slit on each side, and the
front one has about nine : the former, with the exception of the
seventh, are broadest across the posterior margin, as is also the case
in the closely allied AVest-Indian C. pticeus, whilst in C. spiniger
the greatest diameter is across the laminae of insertion in front of
tiie notch. The jugal sinus appears to be rather deeper than in the
latter species. The specimens from Stewart Island, presented to
the British Museum by Mr. C. Traill, agree in all respects witli this
species ; the form, sculpture, and the insertion-plates are quite the
same.
:
114. Chiton (Schizochiton) incisus.
Chiton incisus, Soiverhy, Proc. Zool. Soc. 1841, p. 61 : Peeve, Conch.
Icon. fig. 43.
Chiton elongatus, Peeve, I. c. figs. 40 a, h.
Schizochiton incisus. Gray, Proc. Zool. Soc. 1847, p. 169 ; Shuttle-
worth, Bern. Mittheil. 1853, p. 68 ; H. S¡- A. Adams, Genera Pec.
Moll. vol. i. p. 477, pi. 54. figs. 6, 6 a.
Hah. Island of Zebu, Philippines (Cuming); Paines Island,
Torres Straits (Ince) ; Clairmont aud Bird Islands, N.E. Australia
( Coppinger).
The mantle is thick, of a somewhat spongy texture, alternately buff
and dark brown, the latter colour falling opposite the middle of the
valves and forming interrupted irregular narrow stripes. The spines
upon it are very short, scattered, and of two colours, brown and
white. The raised ridges, generally six in number on the terminal
valves, but sometimes varying to seven or eight, and two on the
central ones, are remarkable in being studded with minute blackish
heads. The longitudinal fine ridges are peculiarly flat-topped,
those on the central areas being straight, whilst on the lateral areas
and the front valve they are wavy or zigzag. The lamina of insertion
in the front valve is thin, externally striated, with six notches
corresponding to the radiating costæ on the outer surface. In the
central valves the lamina is considerably produced in front, with a
single small slit on each side ; in the last valve it is thickened
posteriorly, interrupted in the middle by a large sinus, is coarsely
striated on the outside, and is slit in three or four places. The interior
of the valves is greenish, stained with brown in the middle.
I
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115. Chiton (Macandrellus) costatus. (Plate VI. fig. F.)
Acanthochites costatus, H. Adams ^ Angas, Proc. Zool. Soc. 1864,
p. 194 ; Angas, I. c. 1867, p. 224.
Macandrellus costatus, Dali, Bull. U.S. Hat. Mus. i. p. 81, fig. 40
(dentition).
Hab. Port Jackson (Angas and Coppinger).
The single specimen before me, preserved in spirit, shows the
girdle to be of a pale ,huff colour, thick, fleshy, the outer margin
being delicately ciliated with a minute fringe of white spicules.
The tufts of spicules are seven in number along each side, and four
surrounding the front valve. The middle of the central valves is
occupied by a raised, transversely substriated flattened ridge, on each
side of which the surface is granulated or rather squamose, the
scales being flat, imbricating, rather large, and disposed in rather
regular series. The lateral areas are well defined by a raised keel.
The front valve has five radiating costæ, and apparently the same
number of slits in the thin lamina of insertion, of which the three
central are quite distinct, and the two outer ones only feebly indicated.
The single notch on each side the intermediate valves is
also very slight. The posterior valve has a raised, somewhat ex-
centric and pointed mucro, from which six more or less distinct
radiating ridges descend to the margin, beneath which the lamina
of insertion is scalloped by a similar number of notches.
All ;
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116. Chiton (AcanthocMton) ashestoides. (Plate VI. fig. G.)
Shell small, greyish brown, with a pale line on each side the
middle of the central valves, slightly converging behind, leaving a
dark wedge-shaped space between them. Surface covered with a
coarsish granulation, the granules being somewhat flattened, and
those a t the vertex of the central valves rather smaller than tho
rest. The lateral areas are not defined in these valves ; the posterior
curved margins are produced in the middle, at times almost forming
a riglit angle ; their insertion-plates are large, thin, produced anteriorly,
with a very slight notch quite close to the hinder margin on
each side ; the sinus between them in front is deep and arcuate.
The first valve has a straighter posterior margin than the succeeding
ones, and a semicircular outline in front ; the lamina of insertion
is rather deep, thin, feebly striated exteriorly, and interrupted
by five very small subequidistant notches. The last valve is conspicuously
small, transversely suhovate, depressed-conical, with a
nearly central mucro ; insertion-plate very large, laterally produced,
with only two notches behind. Interior of the valves bluish.
Mantle very minutely spinulose, hearing very conspicuous compact
tufts of silky spicules along the sides, not at all unlike in their fibrous
texture th a t of asbestos. Length 15 millim., width of the broadest
central valve 5^.
Bab. Elinders Island, Bass’s Straits (Joseph AlilUgan) ; Port
Molle, Queensland (Coppinger).
If