that published by Reinhardt;
but the moulting of the scales on the peduncle, the presence of
scales and of points of a different nature, the method of
attachment by cement, the conversion of the discs into a cup,
&c., seem not to have been known to this naturalist. Reinhardt
states that the points on the peduncle will scratch Iceland spar,
and that, apparently, they are formed of phosphate of lime: in
the case of the closely-allied _L. dorsalis_, I must believe that
the scales or beads on the peduncle are formed of carbonate of
lime, for they were quickly dissolved with effervescence in
acetic acid; and the star-headed points, which are subsequently
developed under the calcareous scales, appeared to me, under the
compound microscope, to be formed of a horn or chitine substance.
Reinhardt states that the basal point of the peduncle is arched a
little under the lowest disc, and there forms for itself a slight
furrow (as represented in the lateral view, Pl. VIII, fig. 2);
but in the burrows examined by me, this furrow or depression did
not really exist, the appearance resulting from the basal margin
of the lowest disc, projecting beyond the wall of the cavity by
the amount of its own slight thickness.

* * * * *

We will now proceed with our generic description.--

_Animal's Body._--This, as already stated, is partially lodged within
the peduncle. The prosoma is rather largely developed.

The _Mouth_ is placed at a moderate distance from the adductor muscle.

The _Labrum_ is moderately bullate, with a row of blunt bead-like teeth,
mingled with fine bristles, on the crest, which in the middle part is
generally somewhat flattened.

The _Palpi_ are blunt, and even squarely truncated at their ends; they
are of large size, so that, if they had been half as large again, or
even less, their tips would have met.

_Mandibles_ (Pl. X, fig. 2), with three nearly equal large teeth, and
the inferior angle produced, broad, and strongly pectinated: in the
interspaces between these teeth there are, in all the species, some very
fine teeth or pectinations, which are seated a little on one side of the
medial line. The mandibles are somewhat singular from the size of the
transparent flexible apodemes (_a_ _a_) to which the muscles are
attached; these are oval and constricted at their origins: in _L.
dorsalis_ they are roughened with little points