LYROPUPA. 247 



7. LYROPUPA TRUNCATA Cooke. PL 21, fig. 4. 



The shell is rimate; sinistral, cylindrical, dark brown, 

 elathratulate, with about 14 well developed lamelliform costae 

 011 the last whorl (between the costse 5-8 minute stride) and 

 with 3-4 raised spiral striae on each whorl. Spire cylindrical ; 

 apex almost flat, giving the shell a truncate appearance. 

 Suture simple depressed. Whorls 5, the embryonic without 

 transverse costae but with numerous minute close spiral striae, 

 increasing rather rapidly; the rest convex, clathratulate, in- 

 creasing slowly; the last slightly narrower than the penulti- 

 mate, with two indistinct shallow, longitudinal depressions 

 corresponding to the palatal plicae. Aperture perpendicular 

 quadrate-ovate, with 7 folds, viz. : the angular lamella slightly 

 arcuate, extending nearly to the margin of the peristome; 

 the parietal a little deeper-seated, strongly developed; and, 

 a minute dentiform infraparietal lamella; a deeply seated 

 obliquely entering, but well developed columellar lamella; 

 three nearly parallel palatal plicae, the upper extending nearly 

 to the margin of the peristome, the lower more deeply seated 

 and in addition to these a very short, deeply seated basal plica. 

 Peristome continuous, slightly expanded. 



Length 2.6, diam. 1.66, aperture 1.1 mm. 



Hawaii: Kohala Mts. (Thaanum). Type 15411 Bishop 

 Museum ; paratype in Thaanum coll. 



Lyropupa truncata COOKE, Occasional Papers of the B. P. 

 Bishop Museum, iii, 1908, p. 211, text figure. 



An extremely rare species of which only a very few speci- 

 mens have been taken. The only close relative known at 

 present is L. clathratula, from which it is easily distinguished 

 by its much blunter summit and more numerous apertural 

 teeth. Unlike all of the other Lyropupas except clathratula, 

 the ribs are thin with membranous edges. The spiral striae 

 are further apart than in any other species. 



Section Lyropupilla, n. sect. 



Sinistral Lyropupas with a low, short angular lamella, and 

 without spiral striation on the lower whorls. Type Lyropupa 

 spaldingi. 



