552 Mr. J. C. Melvill on the 
superne rotunde angulatis, ultimo anfractu circa novem costis 
predito, spiraliter arcte bino lirarum ordine succinctis, interstitiis 
inter costas cavernosis ; apertura ovato-oblonga, labro incrassato, 
intus 4-5-denticulato; columella fere recta, omnino cinereo- 
cerulescente, lapidis fissilis colore preesertim instar. 
Long. 18, lat. 8°50 mm. 
Though shouldered just below the sutures, the roundly 
noduled ribs of this species, thickly crossed by thin spiral 
lines, the interstices between the coste being deeply cavernous, 
amply characterize it. Indeed, we know no species nearly 
comparable ; and another very special point of distinction is 
the slate or dull indigo-coloured aperture, labial and columellar 
area, which seems constant, being present, without any 
deviation, in all the examples I have examined. The only 
Sistrum at all comparable appears to be S. anawares, Duclos, 
formerly esteemed a Purpura. 
Natica (Hunatica) tela-aranec, sp. n. 
(PI. 1X. fig. 2:) 
N. testa subperforata, ovato-conica, solida, alba, castaneo-variegata ; 
anfractibus 5, quorum apicales tres subvitrei, brunnescentes, 
nitidi, perleves, ceeteris ad suturas impressis, leevibus, infra (juxta 
suturas) spiraliter flammis castaneis decoratis, inde ad_ basin 
intricatione intertexta notata, ultimo anfractu cxeteros magnopere 
superante ; apertura lunari, albida ; peristomate albo, nitido, con- 
tinuo, subeffuso, margine columellari obliquo, albo-brunnescente, 
callo nitido brunneo; umbilicum profundum semiobtegente. 
Alt. 11, diam. 10 mm. 
Allied to N. Raynoldiana, Récluz, than which it is much 
smaller, at the same time being differently marked and 
coloured. Indeed, the pattern is intricate and somewhat 
involved—a mesh of textile network, with occasional clear 
spaces disposed spirally, giving an obscurely white-banded 
effect, notably just below the sutures. ‘The umbilicus is half 
hidden by a shining brown callus, the peristome being white, 
continuous, slightly effuse without. In the example taken as 
the type the greater part of the body-whorl is dorsally without 
the chestnut involved pattern; no doubt this is accidental. 
Another ally is N. sanctw-helene, HK. A. Sm.; both this, 
N. Traillii, Reeve, and N. buriasensis, Récluz, show slight 
yoints of relationship; the brown callus of 7’radldit is similar, 
but in all the pattern of marking is quite distinct, as also are 
the apical whorls. 
