92 AURICULID^. 



surrounding the umbilical region, which is narrow and rather 

 inflated ; aperture slightly oblique, narrow, sinuate, rounded in 

 front ; body of the penultimate whorl bearing two oblique plaits, 

 the lower of which is stronger ; columellar plait strong, trans- 

 verse, bifid ; peristome orange-coloured, expanded and thickened ; 

 right margin bearing within a thick longitudinal ridge, which 

 is cut out at its upper part and denticulated at the remaining ; 

 columellar margin spreading, free. Length 32-37, breadth 

 18|-20 mill. 



Auricula (Cassidida) rugata, Menke, Moll. Nov. Holl. p. 7. n. 15. 

 Kiist. Auric, p. 27. t. 4. f. 1, 2. 

 Jay, Catal. 1850, p. 265. n. 6173. 

 Auricula coelata, Hombr. andJacq. Voy. Pole Sud, Zool. v. p. 33. 



pi. 9. f. 4-6. 

 Auricula rugulata, Forbes in Voy. Pattlesn. App. p. 362. 

 Cassidida rugata, H. and A. Adams inProc. Zool. Soc. 1854, p. 31 ; 

 Gen. rec. Moll ii. p. 238. 

 Pfr. Syn. Auric, n. 123 ; Mon. Auric, p. 120. 



Hob. Victoria River, Port Essington, Australia. 



§ 3. Imperfectly known sjiecies. 



17. Cassidula bugulata. 



Shell imperforate, conic-oblong, striated spirally, and decus- 

 sated with more distant spiral ridges and minute longitudinal 

 ribs, grey ; spire conic, with the apex pointed ; whorls nine, 

 scarcely convex, the upper ones banded with brown, the last 

 forming nearly four-fifths of the total length, attenuated and 

 marked with a white keel at base ; aperture oblong, gaping ; 

 parietal plaits two, oblique, distant ; columellar plait twisted, as 

 if composed of two ; peristome much thickened ; internal callus 

 emarginate superiorly and in the middle, denticulated on its 

 remaining part. Length 33, breadth 19 mill. 



Auricula rugulata ?, Jacquinot in Voy. Pole Sud, Atlas, Moll. pi. 9. 



f. 10-12. 

 Auricula rugulata, Rousseau in Voy. Pole Sud, Zool. v. p. 35. 

 Cassidula rugulata, Pfr. Mon. Auric, p. 122. 



Hab. Arrow Islands. 



18. Cassidula mioxi. 



Shell pyramidal, very minutely striate, uniformly brown or 

 pale yellow, with chestnut-coloured bands; spire moderate, conic, 

 acute ; last whorl rather ventricose, contracted at base ; aperture 

 narrow; palatal plaits two, distant; columellar plait twisted, 



