Zoological Society. 143 



variegatd ; apice marginali eroso, retusissimo ; labia albo, posfice 

 aurantio, inargine subrecto ; aperturd albido-carulescente. 



Long. 1-16 ad 1-28 ; lat. 0-80 ad 0-84 ; conv. 0-46 ad 0-54 poll. 



Var. /3. T. ovatd, post ice siibtruncatd, tenuiusculd ; apice ante mar- 

 ginem inserto, deroso. 



Long. 1-24 ad 1-28 ; lat. MO ad 1-14 ; conv. 0-52 ad 0-56 poll. 



Hab. Cagayan, province of Misamis, island of Mindanao : found 

 on stones in a large river. 



Although these two varieties appear to differ from each other in 

 the position of the summit, I do not think they can be separated. 

 Nevertheless the operculum vai'ies perceptibly, and if their respective 

 characters proved constant, which it would be necessary to verify by 

 examining a certain number of specimens, then alone could one be 

 distinguished from the other. The surface of this Navicella shows 

 upon the anterior side longitudinal striae, as deeply impressed as the 

 transverse ones. 



The operculum of the type is blackish throughout, except at the 

 base, which is of an orange-red. The anterior side is notched. The 

 dental apophysis is linear, smooth, a little raised, faintly striated both 

 longitudinally and transversely. The external margin of this tooth 

 projects but little, and its inferior part shows the commencement of 

 a crest, but without teeth. 



The operculum of the variety is of a rosy colour, with the inferior 

 margin of an orange-red ; the anterior side is more slightly notched 

 in the middle, its dental apophysis projects rather more, and is linear, 

 smooth, and divided by a longitudinal groove. The external margin 

 of this tooth is narrow, without any trace of a denticulated crest at 

 its base. 



3. Navicella suborbicularis. Sowerby, Cat. Tank. App. p. 10. 

 No. 1092 ; Recluz in Guerin, Rev. Cuv. 1841. p. 377. No. 10. 



Var. ft. Recluz, 1. c. ; Rumph. Mus. Amb. p. 40. f. 0. Optime. 



Var. y. Minori, tenuiori. 



Hab. ad Insulas Pliilippinas. From the island of Camiguing : found 

 on stones in mountain-streams. Var, ft, from Cagayan, province of 

 Misamis, island of Mindanao : on stones in a large river. Y?lv. y, 

 from Banguey, province of North "\1ocos, island of Lu9on : found on 

 stones in a small stream. 



I see neither in the general form nor in the operculum of these 

 varieties any character sufficient to distinguish them from the type : 

 the colour alone is variable. 



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. Navicella Luzonica, Souleyet. N. testa ellipticd, rufo-fuscd 

 sen olivaced unicolori seu nigro obsolete reticulatd aut punctatd, 

 lateribus compressiusculd , dorso valde convexd, solidd ; apice ad 

 marginem posterior em incurve, subintegro ac eroso ; labio semi' 



