576 PROCEEDINGS OF THE ACADEMY OF [DeC, 



lamella, but otherwise hardly differs from pale, long specimens of C. 

 a. spicata. 



In C. agna the lunella only weakly joins the upper palatal plica. 

 This is not well shown in the original figure. 



Section HETEROZAPTYX Pils. 

 Clausilia oxypomatioa Pils. 



Specimens received from Ogachi, Oshima, are smoother than the 

 type of this species, the striation rather indistinct except on the last 

 whorl, and the clausilium is quite perceptibly broader. 

 i^Length 12, diam. 2.8 mm.; whorls 9^. 

 11, " 2.6 " " 6.' 



Section ZAPTYX Pilsbry. 



In this section we group numerous closely related forms distributed 

 throughout the Ryukyu chain, from the Southwestern Group to 

 Kagoshima Bay. 



Key to Species of Zaptyx, s. str. 



a. — Upper palatal plica very long; spiral lamella reduced to a short 

 lamella in the region of the lunella. 

 b. — 10.5 to 12.5 mm. long, with 9^ to 10 whorls; striatulate. 



Ryukyu, C. dolichoptyx. 



b^. — 8.5 to 9.5 mm. long, with 8 to 8^ whorls ; last half whorl sharply 



and finely striate. Ryukyu, C. d. micra. 



t}. — Upper palatal plica moderate or short, much shorter than the 

 lunella. 

 h. — Subcolumellar lamella wholly immersed; whorls quite convex, 

 smoothish, but finely and sharply striate behind the lip. 

 c. — 9 to 10 mm. long, 2.2 to 2.3 wide. Okinoerabushima, 



C. sarissa. 

 c^. — 8 to 9 mm. long, 2 to 2.1 wide; last two whorls less convex. 



Nakanoshima, C. nakanoshimana. 



b^. — Subcolumellar lamella emerging; whorls less convex, 



c. — Upper palatal plica very short; inferior lamella not con- 

 tinuous within with the lamella inserta. 

 d. — Last 3 or 4 whorls finely and sharpty striate; superior 

 and spiral lamellae weakly continuous. Yaeyama, 



C. yaeyamensis. 

 d^. — Smoothish throughout, or only the last whorl striate; 

 superior and spiral lamellae widely separated. 

 e. — ^Smoothish, early whorls not attenuate, Satsuma, 



C, hirasei. 

 &. — Back of last whorl striate; spire attenuate above, 



Kikai, Tokuno, C. kikaiensis. 



c^. — Upper palatal plica moderate; inferior lamella continuous 

 with the lamella inserta, penetrating inward as far as the 

 spiral lamella; fulcrum and parallel lamella well devel- 

 oped . apex larger than the preceding species. 



