ARCHYTJ.A. 87 



Genus ARCHYTJKA, Costa, 1869. 



I have added to this a\'iius a number of species described as Ad- 

 eorbis, but which are related to the following type species by the 

 characters of the shell. 



A. DELICATUM, Phil. PI. 30, fig. 6. 



Moderately umbilicated, thin, semipellucid, white; whorls 82, 

 convex, the last large, suture well impressed, base a little flattened ; 

 surface smooth, microscopically decussated ; aperture oval, peristome 

 simple, nearly continuous. Diam. 1*1 mill. 



Norway ; fossil in Sicily. 

 Var. EXPAN6A, Sars. PI. 30, fig. 7. 



Shell and aperture more oblique, dilated below. Diam. 1*4 mill. 



Norway. 

 A. SUTURALE, A. Ad. PL 30, figs. 4, 5. 



Rather narrowly umbilicated, very finely concentrically striated, 

 thin, semipellucid, white, spire a little elevated; whorls somewhat 

 convex, rapidly increasing, suture deep ; aperture rounded. 



Diam. 1'5 mill. 



Tsu-Sima, Japan. 

 A. CORNICULUM, A. Ad. PI. 30, figs. 8, 9. 



Umbilicus narrow, defined by an angle, white, translucent, very 

 minutely striated ; w r horls somewhat convex, rapidly increasing, the 

 last rounded, large ; aperture round. Diam. 2 mill. 



Mino-Sima, Japan. 



A. DIAPHANUM, A. Ad. PI. 30, figs. 10, 11. 



Narrowly umbilicated, globose, transparent ; whorls rounded, the 

 last inflated ; aperture round. Diam. 1'5 mill. 



Gotto Is., Japan. 

 A. EXQUISITUM, Jeffreys. PI. 30, figs. 12, 13. 



Rather widely, deeply umbilicated, white, rather thin, transparent 

 and glossy, microscopically decussated, the crossings slightly nodose ; 

 whorls 3, convex, with deep suture; aperture obtusely subtriangular. 



Diam. 1'75,-alt. 2'5 mill. 



Mediterranean Sea. 



Subgenus PSEUDORBIS, Monts., 1884. 

 A. GRANULUM, Brugnone. PI. 30, fig. 14. 



White, subglobose, spire a little exserted, whorls 3, spirally ribbed, 

 ribs elevated, scarcely umbilicated, peristome subcoutinuous. 



Diam. 1.5 mill. 



Mediterranean Sea. 



