422 



PROCEEDINGS OF THE ACADEMY OF 



' [July, 



obsolete upper palatal fold. The clausilium is the same as in the 

 typical form. The tip of the spire is sometimes lost. 



Length 28, diam. 6.3, longest axis of aperture 7.2 mm. 



Length 28.7, diam. 6, longest axis of aperture 7.2 mm. 



Clausilia excellens Pfeiffer. PL XXIII, fig. 43. 



This species was originally described by Gould as G. prceclara, 

 but this name being preoccupied it was changed by Pfeiffer to (7. 

 excellens. The species was known to Pfeiffer by Gould's descrip- 

 tion only. 7 Through the kindness of Prof. William H. Dall I am 

 able to give a figure of the type specimen, from 

 Loo Choo, in the National Museum. 



It differs from C. crenilabium in the slightly 

 stronger striation and the better development of the 

 interlamellar crenulation; and from C. crenilabium, 

 ptychochila and Bernardii in the grooving of the 

 top of the inferior lamella, which is almost bifid. 

 In C. crenilabium and C. JSernardii the inferior la- 

 mella is only bifid far within, in a dorsal position, 

 as shown in PI. XXIII, fig. 25. In t7. excellens 

 this bifid structure has apparently moved downward 

 to the lower end of the lamella. 



The clausilium of C. excellens is still unknown, 

 as the type specimen has not been opened ; and the 

 subgeneric position of the species cannot, therefore, be considered 

 certain. It may possibly be a Luchuphcedusa. 



Group of C. munus. 



A group of uncertain systematic position, probably referable to 

 Tyrannophcedusa rather than to Hemiphcedusa ; but more material 

 and further study is needed to determine to what extent Hemi- 

 phcedusa is heterogeneous, and how it may best be subdivided. 

 The heavy thickening of the distal end of the clausilium on the 

 columellar side, and its short form, remove the species described 

 below from Hemiphcedusa, but it differs from the typical forms 

 of Tyrannophceditsa in the comparatively few-whorled shell and 

 in details of the palatal armature. 



7 See p. 409, footnote No. 2. There is a very poor figure of C. excellens in 

 the Conchologia Iconica, XX, PL X, fig. 89. 





