676 PROCEEDINGS OF THE ACADEMY OF [1900. 



palatal plicae are much as in C. aurantiaca, but the clausilium 

 denies C. iotaptyx entrance in any group of Hemiphcedusa. 



Section TYRANNOPH^EDUSA nov. 



Many-whorled, with distinct sinulus, deeply placed inferior 

 lamella, very remote throughout from the superior lamella, the 

 clausilium narrower than in Euphcedusa, tapering and oblique at 

 the much-thickened apex. Other characters as in the 0. jos group 

 of Eaphcedusa. I propose this section for the following remark- 

 able species : 

 Clausilia mikado n. sp. Pi. XXIV, figs. 10, 11, 12. 



Shell rimate, the lower half swollen, upper half exceedingly 

 attenuated ; livid gray, becoming dull red where worn, and over- 

 grown with alga in most specimens seen. 



Sculptured with crowded, very fine strise, on the last two whores 

 becoming very much coarser, last whorl rather irregularly rib- 

 striate. Apex obtuse and globose; whorls 18, the earlier 8 or 10 

 not increasing in diameter, e*ven decreasing a little; the next few 

 whorls gradually, slowly increasing, the last 4 whorls forming the 

 rather swollen lower half of the shell's length; last whorl de- 

 cidedly higher than the preceding, tapering, compressed at the 

 sides. Sutures impressed. Aperture small, oblique, retracted 

 above and below, irregularly pyriform, the sinulus strongly devel- 

 oped, high and narrow; peristome white, expanded and thickened, 

 continuous, emarginate above, where it is built out far beyond the 

 whorl. Superior lamella marginal, vertical, well developed, con- 

 tinuous with the spiral lamella. Inferior lamella not visible in a 

 front view, deeply immersed, continuing very distant from the 

 superior lamella within, but giving off a low branch toward it. 

 Subcolumellar lamella emerging, sometimes continued to the margin 

 of the peristome, and more or less distinctly bounded by grooves. 

 Principal plica strong and long, extending nearly to the lip, and 

 inward to the ventral side of the whorl. Upper and lower palatal 

 plicae short, oblique and parallel, connected by a nearly straight, 

 narrow, rather weak lunella, which, however, is hardly connected 

 with the upper palatal, and is lateral in position. Clausilium 

 (PI. XXV, figs. 37, 38, 39) strongly thickened at the sides and 

 end, and especially along the columellar margin near the apex (fig. 

 38), abruptly emarginate on the columellar side posteriorly, the 



