212 RETUSA. 



croscope showing arcuate growth lines and extremely fine descend- 

 ing spiral striae toward the base. Aperture as long as the shell, 

 narrow and nearly linear above, pyriforra at the base : lip arcuate, 

 simple, sharp ; columellar margin convex ; columella thick, twisted, 

 provided with a well marked fold. Color uniform hyaline white 

 (B. D. & D.). 



Eastern basin of the Mediterranean. 



Cylichna ( Cylichnina) crossei B. D. & D., Moll. Mar. Rouss. i, p. 

 526, pi. 64, f. 9-11. 



Smaller than JR. umhilicata, more regularly oval, not contracted 

 at the summit nor enlarged at the base and the aperture is not 

 wider at summit than in the middle. 



R. STRiATULA Forbcs. Unfigured. 



Shell oblong, cylindrical, milk-white ; transversely undulately 

 striated, longitudinally obsoletely striated ; vertex subtruncate, con- 

 cave; spire visible ; aperture linear above, dilated below, Length 

 one-eighth inch (Fbs.). 



Rio, Macri, Servi, Crete, etc., ^gean Sea (Forbes) ; Bay of Na- 

 ples (Tiberi). 



Bulla striatula Fbs., Rep. ^gean Invert. Brit. Asso. Rep. for 

 1843, p. 188. — Utriculus striatulus Jeffr., Ann. Mag. N. H. (4), 

 vi, p. 84. — [? Bulla ( Cylichna') pyramidata A. Adams, teste Jeffreys]. 

 — Cylichna hoernesi Weinkauff, Conchyl. des Mittelm. ii, p. 197 ; 

 Bull. Mai. Ital. iii, p. 92. — Cylichna euneata Tiberi, Journ. de 

 Conchyl. 1868, p. 181, teste Monterosato, Journ. de Conch. 1878, 

 p. 159. — Weinkauff, Bulletiuo Malacologico Italiano, iii, p. 92, 

 1870. 



This species is still unrecognizable to those who have not seen 

 authentic specimens. It is a pity that so many of the Mediterra- 

 nean shells are still insufficiently described and unfigured, notwith- 

 standing the large literature upon them, and the multitude of lists 

 by Jeffreys, Monterosato and others. 



R. NiTiDULA Loven. PI. 23, fig. 54 ; pi. 60, fig. 5. 



Shell thin, subpellucid, white, oblong-cylindrical, rather narrow, 

 more than twice as high as wide ; slightly tapering toward the apex, 

 where it is obtusely truncated and narrowly perforated in the mid- 

 dle, the spire indistinct. Aperture very narrow in the middle, 

 dilated below, the outer lip projecting a little above the vertex, 



