ATY8. 263 



We have above expressed the opinion that this group and the next 

 may eventually be removed from Atys. 



DINIA H. & A. Adams, 1854. Shell ovoid, subtruncate above, 

 longitudinally striated ; columella abruptly truncated below, ending 

 in a tooth-like prominence. Type A. dentifera Ad. 



The next two groups do not appear to offer any differential 

 features of importance. All are characterized by the prominent 

 truncation of the columella and the absence of a fold above the 

 vertex. 



Roxaniella Monterosato, 1884. Shell diaphanous, date-shaped, 

 with spiral plicate sculpture ; columella with a thickened sinuosity, 

 simulating a fold. No fold above the vertex. Type A. jeffreysi. 

 This group seems to be synonymous with Dinia. 



Weinkauffia A. Adams. Type A. diaphana Arad. This group 

 offers no tangible differences from Dinia. 



Subgenus ATYS Montf. 



A. NAUCUM Linne. PI. 28, figs. 11, 12, 13, 14, 15, 16. 



Shell globose-oval, inflated, widest at the middle, solid ; white 

 under a thin buff or chestnut cuticle. Vertex narrowly concave ; 

 body whorl sculptured throughout with engraved spirals, much 

 closer and uneven toward the ends, more spaced or altogether 

 absent in the middle; base concave around the rimate umbilicus. 

 Aperture as long as the shell,- the lip rising high above the vertex 

 and angularly plicate there ; columella vertical, angularly plicate 

 or truncated in the middle ; outer lip everywhere well curved. 



Alt. 41, diam. 29 mill., often smaller. 



Singapore, Borneo and Philippines to Torres Straits, eastward to 

 Viti Is., westward to Red Sea and Madagascar. 



Bulla naucum L., Syst. Nat. x, p. 726. AD., in Thes. Conch, p. 

 584, pi. 124, f. 107-109. Atys naucum SOWB., Conch. Icon. f. 1. 

 E. A. SMITH, Zool. Coll. Alert, p. 86. BRAZIER, P. L. S. N. S. W. 

 ii, p. 84. MARTENS, Mobius' Reise n. Mauritius p. 302. COOKE, 

 Ann. Mag. N. H. (5), xvii, p. 131. Atys cymbulus MONTF., Conch 

 Syst. ii, p. 343. B. (J..) ferruginosa A. AD., Thes. ii, p. 585, pi. 

 124, f. 110 (not B. ferruginosa Gmel. p. 3432, young Cyprcea') ; 

 Ann. Mag. N. H. (4), ix, p. 344. Atys ovoidea AD., Thes. Conch. 



