1908.] NATURAL SCIENCES OF PHILADELPHIA. 565 



the most closely related species, but it differs in sculpture ; it has not 

 the fine, thread-like striation of C. tripleuroptyx , being more glossy, 

 paler colored and less opaque. 



As in C. aculus, the palatal armature varies. In most examples 

 seen there are three palatal plicae below the principal plica, the second 

 either pUciform or punctiform (as in fig. Sd). Sometimes there are 

 six plicae, the 3d, 4th and 5th very small, scarcely visible inside by 

 reflected light (fig. 3e). 



Section STBREOPH^DUSA Boettger. 

 Clausilia japonica Crosse. 



The typical form of this species is found around Tokyo. The exact 

 locality of the types was not known, but the Tokyo shells agree so fully 

 with them that this place may be considered the type locality. 



The shells are coarsely rib-striate, the striae simple (not split), and 

 on the last whorl there are about five striae in one millimeter. The 

 spiral lamella penetrates inward to the middle of the ventral side; 

 the inferior lamella is much longer. There are two palatal plicae, 

 an upper and lower, below the principal, and in some examples there 

 is the weak rudiment of a lunella near the lower palatal plica, and a 

 second low nodule or plica just below the upper palatal plica. The 

 size of Tokyo specimens is rather variable. 



Length 29.0, diam. 6.5 mm. ; whorls IH. 

 25.5, " 6.5 " " 11." 



26.5, " 6.2 " '' 11. 



The forms I described as var. perstriata and var. perobscura are close 

 to typical japonica in sculpture. It is hard to decide what forms of 

 so variable a species call for special names. Besides those now recog- 

 nized, there seem to be several races, which may for the present remain 

 und escribed. 



The largest form of C. japonica I have seen was sent from Yakuenji, 

 Izumo, by Mr. Hirase (No. 1594). The shell is rich chestnut colored 

 when unworn, about as finely striate as C. j. nipponensis, and, like that, 

 it has upper and lower palatal plicae only, the lower one quite small. 

 The spiral lamella runs inward to the middle of the ventral side, the 

 inferior lamella being longer. Except in having no sutural plica, this 

 form agrees with C. hilgendorfi Martens. No other Stereophcedusa is 

 known to have a sutural plica, so that it is possible that its recorded 

 presence in C hilgendorfi may be an abnormal development, in which 

 case, this form is evidenth' C. hilgeyidorfi. Specimens from Yakuenji, 

 Izumo, measure: 



