144 Zoological Societij. 



lunari aurantio, anticl rectiuscnlo ; aperturd albido-ccerulescente, 

 margine posteriore laterali nigrescente . 



Nav. Luzonica, Souleyet, Rev. Cuv. 1841. p. 375. No. 6. Junior. 



Var. (3. T. olivaceo-fuscescente, maculis minimis lutescentibus vix 

 nigrescente marginatis irroratd. 



Var. y. T. riifo-fuscd immaculatd ; apice deroso, convexo. 



Var. L T. rufo-fuscd, postice tenuissime nigro et lutescenti longi- 

 tudinnliter lineolatd,'maculisque minimis lutescentibus conicis nigro- 

 marginntis, obsoletisque (sub lente) pictd. 



Var. e. T. rufo-fuscd, inter oculum et laminam maculis minimis sub' 

 nigrescentibus adspersd. 



Var. ^. T. minori, tenuiori, oUvaced, postice lineolatd, supra nigra 

 tenuissime reticulatd, antice maculis squayniformibus pictd, labia 

 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 c from Cagayan, pro- 

 vince of Misamis, island of Mindanao : on stones in a large river. 

 Var. e, fi-om the mountains of the island of Negros : found on the 

 rocky bed of a small stream. 



The individual which served as t}'pe 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 

 very open : some are altogether rose-coloured, others rosy on one 

 side, yellow on the other, and blackish in the middle ; others again 

 almost entirely of a bluish tint, and mingled with these various co- 

 lours. 



The summit, sometimes almost entire or decorticated only, is at 

 other times entirely eroded at its inferior surface ; it is prolonged 

 upon the posterior margin of the opening, though not beyond, and 

 there it is worn away, as if it had been rubbed upon a grindstone. 



5. Navicella Cumingiana. N. testd orbiculari seu ovatd, convexd, 

 solidd, vix striata luteo-fuscescente, lineis concentricis nigris un- 

 dulatis arcuatisve interdum reticulatis cinctd ; apice marginali 



