158 
Var. ¢. T. fuscescente maculis linearibus albidis nigro acute margi- 
natis obsoletis sparsis variegatd ; apice purpurascente ; labio et 
margine aperture dilute fuscis. : 
Long. 0°80 ad 1°32; lat. 0°76 ad 0°92; conv. 0°24 ad 0°48 poll. 
Hab. Var. 5 and y from Cagayan. Var. a and e from Banguey, 
province of North Ylocos, island of Lugon: found on stones in a 
mountain stream. Var. y, island of Guimaras, on the rocky bed of 
a small stream. Var. 6, rocky bed of a stream in the mountains of 
the isle of Negros. The type itself is found at Pasuguing, province 
of North Ylocos, island of Lucon. 
Operculum almost square, thin, of a rose-colour, cut squarely an- 
teriorly, with a projecting, obtuse, linear tooth, which is divided by 
a slightly impressed longitudinal groove ; the right margin very nar- 
row, very thin, and without crest. 
It is possible that this species may prove only a stronger, more 
robust state of the Nav. tessellata ; nevertheless it differs in its gene- 
ral form, and its operculum also shows some differential characters. 
7. NAVICELLA TESSELLATA, Lamarck. 
Var. a. T. lateribus angustatd, subrectis ; sub epidermide lutescente 
lineolis violaceis seu purpureis creberrimis, et maculis conicis con- 
centrice seriatis pictd ; vertice recto, luteo ; labio triangulari, antice 
subarcuato, lateribus prolongato. 
Var. 6. T. ut in var. a, sed postice subemarginatd, griseo-fuscd, 
maculis minoribus luteo-fuscescentibus conicis crebre pictd ; apice 
dilute purpurascente, recto; labio subtriangulari, ungusto, roseo, 
antic arcuato. 
Var. y.? T. oblongo-ellipticd, antic? et postice rotundatd, crassiore 
sive oblongo-acutd, lateribus angustatd, nigerrimd, apice eroso ; 
labio semilunari, interdum triangulari, latiore, subrecto, lateribus 
non prolongatis. 
An Nav. Clypeolum, var.? credo, sed difficile est probandi sine 
operculo. 
Long. 0°80 ad 0°92; lat. 0°76 ad 0°92; conv. 0°24 ad 0°48 poll. 
Hab. Var. a, Cagayan: found in a large river on stones. Var. /3, 
from Baccara, province of North Ylocos, island of Lucon : found on 
stones ina placid river. Var. y.?, from Abulug, province of Cagayan, 
island of Lucon: found on stones in a large river. 
Operculum square, a little elongated, narrow, and cut almost 
square anteriorly, with a slight notch towards the apophysis, which 
is slightly curved inwards (instead of being straight or turned back 
wards, as in that of Nav. clypeolum). 'The inclined angle of the 
middle of the left side is deeper, and in this species shows a depres- 
sion or broad canal, in form of a A, the whole length of the apophy- 
sis ; this canal is limited to the left by two slightly raised ribs. 
These characters of the operculum, if they be constant, should 
suffice to avoid all confusion of this species and the one which pre- 
cedes, 
8. NaviceLnia tineata, Lamarck. 
Var. a. T. oblonga, postice acuta, luteo-aured, superne lineis spa- 
— diceis radiantibus ex lineolis transversis obumbratis, antice et late- 
