156 
varieties any character sufficient to distinguish them from the type : 
the colour alone is variable. 7 
The operculum is of a pale flesh-colour, flattened with an arched 
notch at the anterior side. The apophysis projecting, smooth, a 
little more arcuated than that of the operculum of Nav. Janelli; its 
external margin is narrower, almost straight, finely crenulated in its 
lower half. The posterior border is very thin and of a dirty red. 
4, Navicritua Luzonica, Souleyet. N. testd ellipticd, rufo-fuscd 
seu olivaced unicolori seu nigro obsoleté reticulatd aut punctatd, 
lateribus compressiusculd, dorso valde convexd, solidd ; apice ad 
marginem posteriorem incurvo, subintegro ac eroso; labio semi- 
lunari aurantio, antic rectiusculo ; aperturd albido-cerulescente, 
margine posteriore laterali nigrescente. 
Nav. Luzonica, Souleyet, Rev. Cuv. 1841. p. 375. No. 6. Junior. 
Var. 8. T. olivaceo-fuscescente, maculis minimis lutescentibus vie 
nigrescente marginatis irroratd. 
Var. y. T. rufo-fuscd immaculatd ; apice deroso, convexo. 
Var. 0. T. rufo-fuscd, postice tenuissime nigro et lutescenti longi- 
tudinaliter lineolatd, maculisque minimis lutescentibus conicis nigro- 
marginatis, obsoletisque (sub lente) pictd. 
Var. e. T. rufo-fuscd, inter oculum et laminam maculis minimis sub- 
nigrescentibus adspersd. 
Var. £. T. minori, tenuiori, olivaced, postice lineolatd, supra nigro 
tenuissime reticulatd, antice maculis squamiformibus pictd, labio 
stramineo, nigrescente circumvallato. 
Long. 1°28 ad 1°60; lat. 0°84 ad 1:12; conv. 0°52 ad 0°76 poll. 
Hab. From Dingle, province of Ylo Ylo, island of Panay: found 
in a placid river on stones. The var. y and 6 from Cagayan, pro- 
vince of Misamis, island of Mindanao: on stones in a large river. 
Var. e, from the mountains of the island of Negros: found on the 
rocky bed of a small stream. 
The individual which served as type to M. Souleyet was young, 
and had been brought home in spirits of wine, which hindered him 
from seeing the black lines which adorn the external surface of this 
Navicella. There is then no difference between his specimen and 
these of Mr. Cuming. 
The operculum of this Navicella is rose-coloured, clouded with 
_ white and blue, but the rose-colour predominates. The notch of its 
anterior portion is somewhat rounded; its subarcuated apophysis 
bears a longitudinal groove more or less impressed; the external 
margin of this apophysis is tolerably large, and rather concave below 
the middle, at the usual origin of the crest, which is wanting in this 
species. The inferior or internal surface is of a pale flesh-colour, 
with a blackish tint on its left margin. The muscular impression 
is rose-colour, very shining, almost square, truncated anteriorly and 
upon the left side, somewhat rounded at its base, straight and oblique 
on the right side, with an acute angle at its base. 
This operculum varies in form and colour; its notch in one indi- 
vidual had the form of a A, or profoundly acute; in others it was 
