551 



12. Navicella suborbicularis (pi. cxviii. f. 30, 31, var. ? 

 pi. cxvii. f. 3), Sowerby, sen., Tank. Cat., Appendix, No. 1092. 



N. testa subrotundata, convexa, griseo rufescente reticulata ; 

 apice rotundo, haud ad marginem extenso; apertura intus au- 

 rantia ; septo angustato ; operculo subquadrato, acute unidentato. 



Rather round in form, very convex, with a rounded apex not 

 reaching the margin. The external surface is reticulated with 

 reddish-grey lines ; the inner part generally presents an orange 

 tint under the septum ; the septum is very narrow. 



Timor; Sowerby. On stones in rivulets, Island of Johanna, 

 Commoros ; Rev. W. Hennah. 



13. Navicella Clypeolum (pi. cxviii. f. 32, 33, 34, 35), 

 Recluz, MS. N. atra, N. radiata, N. Recluzii, Reeve, Conchologia 

 Systematica. 



N. testa, ovali, minutissime striata, subdepressa, rubro nigroque 

 varie tessellata etfasciata; apice parvo, margine apicem superante; 

 septo semicirculari, subconvexo, margine paululum arcuato ; oper- 

 culo subquadrato, acutissime unidentato. 



In this species the apex does not reach the margin, and the 

 external surface is very finely striated. The shell is rather depressed 

 and variously tessellated, sometimes in longitudinal bands, with 

 red and black. The septum is rounded at the posterior, and very 

 slightly arcuated at the anterior margin, with a tendency to con- 

 vexity. The operculum is very strongly toothed. 



On stones in rivers, in several of the Philippine Islands. Cuming. 



14. Navicella variabilis (pi. cxviii. bis. f. 40, 41, 42), 

 Recluz, Pro. Zool. Soc. 1842, p. 155. 



N. testa N. Clypeolo simili, sed margine vix expanso, apice 

 marginali, dorso magis tumido. 



Like N. Clypeolum, but with the margin less spread, the back 

 higher, and the beak more curved, so as to reach the margin. 



Mindinao, Philippines. Cuming. 



15. Navicella Cookii (pi. cxviii. bis. f. 45-47), Recluz, MS. 



N. testa N. suborbicitlari simdi, sed magis ovali, apice marginem 

 tegente, labio latiusculo, aurantio. 



Like N. suborbicularis, but more oval ; the apex bent down so 

 as to reach the margin; the septum a little broader, and of a 

 bright orange-colour. 



One of the Commoro Islands (Johanna). Rev. W. Hennah. 



