, 
$2 HYALINIA PURA. 
Animal white, with two black lines like the preceding [H. crystallina]; cloak 
white, speckled with black. A variety has the shell of a pale horn colour and the 
animal rather darker. 
Under stones, decayed leaves, ete., in woods; not unfrequent. 
This species somewhat resembles the preceding [H. crystallina], but is readily 
distinguished from it, by being larger, more convex, and less shining ; the whorls 
less closely set, and the outer one larger in proportion to the rest. The umbilicus 
also is much larger. It has sometimes been taken for a variety of H. nitidula, but 
differs from that species in being scarcely one-third the size, of a different colour, 
and without any trace of opacity beneath. 
White varieties of this tribe of shells undoubtedly sometimes occur, but these 
are generally mere sports of nature, which, like similar varieties in the higher 
classes of animals, are not perpetuated without the aid of art or domestication ; 
such is not the case with this species, which preserves its characters unchanged 
even when living in the midst of its congeners.”—J. ALDER, Trans. Nat. Hist. 
Soc. Northumb., 1830, vol. i., pt. 1, p. 37. 
Description—The ANIMAL has a white 
and somewhat translucent BODY, some- 
times tinged with yellowish, and covered 
with minute and close tuberculation ; the 
HEAD and DORSUM are of a greyish shade ; 
the black OMMATOPHORES are long and 
rather slender with slightly swollen tips, 
the broad RETRACTORS to which their dark 
colouring is due, are also distinetly visible 
through the dorsal skin as a pair of broad 
blackish lines on each side of the dorsum ; 
the LOWER TENTACLES are comparatively 
elongate and also black, their retractors 
showing through the skin as a fainter black 
line along each side of the body and form . 
the boundary of the darker colouration of the Fic. 120,—Surface sculpture of the pen- 
back ; FOOT-SOLE short, narrow, pale, and lumate whod of 4. guia wer tins 
indistinctly tripartite ; MANTLE whitish, X60 (after microphoto: by Mr. J-W. Jackson 
speckled with black. 
The SHELL is convexly depressed above, and somewhat more convex beneath, 
rather dull, but semitransparent white, and beautifully but delicately sculptured 
by the intersecting spiral and transverse striz, 
which form a beautiful reticulate pattern ; SPIRE 
convexly raised ; SUTURE puckered by the folding 
of the incremental lines; WHORLS 34-4, the last 
being somewhat dilated near the aperture, as in 
H. nitidula ; MOUTH broadly crescentic ; UMBILICUS 
open and somewhat wide, but disclosing all the Fic. 121.—Section throvgh the 
internal spire, and without any basal opacity. shell! of Hyatma pura, showing 
a A - 5 the character of the whorls and 
Diam., 34 mill. Alt., 2 mill. Average weight of umbilical cavity x 8 (from a pre- 
an adult shell about }th of a grain. paration by Mr. F. Khodes). 
When containing the retracted animal, the shell appears of a fawn colour, 
darker towards the apex, but changing to white on the last whorl ; mantle-margin 
as seen through the shell is opaque yellowish-white, marbled with blackish. 
Beneath, the basal surface is sometimes approximately but perceptibly divided into 
quadrants, distinguished by slightly differing colours, the pale section at the mouth 
of the shell is balanced by a nearly colourless section opposite, where the heart and 
renal organ are placed. Adjoining the commencement of the penultimate whorl is 
the dark fawn-coloured liver, while opposite there is the black marbled mantle. 
gO eey, 
The MANDIBLE or jaw is almost a millimetre in pri 
width from side to side, of the usual crescentic 
shape, with distinctly recurved ends; the central fies: 1 
rostrum or beak is not very prominent, though well- : ; 
marked and distinct; the lateral extremities are 
acutely pointed and turned upwards, the line of 
insertion within the tissues of the head is well- Nigool wee 5 
marked, and the chitinous prolongation which forms ulin 30 (Calon "Co. 
the roof of the bueeal chamber is distinctly present. — Louth, Mr. P. H. Grierson), 
