146 AMASTRA, KAUAI. 



Recognizing the affinity of Carelia, it must also be ad- 

 mitted that A. knudseni is closely related to A. kauaiensis, as 

 Mr. Baldwin recognized. 



2. A. KNUDSENI Baldwin. PI. 16, figs. 4, 5, 6. 



Shell imperforate, dextral, oblong-conic, bicarinate. The 

 first 3 1 /.. whorls are slightly convex, forming a conic embry- 

 onic shell; the first whorl is smooth; the second has curved 

 vertical riblets; on folio-wing whorls the riblets become irreg- 

 ular, frequently formed of two or more contiguous striae. 

 The first post-embryonic whorl has rather coarse wrinkles and 

 minute, thread-like striae, and some traces of spiral cords ap- 

 pear upon it. The surface at once becomes more convex, and 

 then angular, forming a shoulder above the middle of the 

 whorl ; below this shoulder it is vertical. After the fifth 

 whorl the characters of maturity appear; the whorl expands 

 more rapidly, the angle gives place to a keel ; on the last 

 whorl a second (periferal) keel appears, the space between 

 them being concave ; the base is convex, and the whole surface 

 sculptured with spiral cords and striae. Color, purplish red- 

 brown, darker towards the apex and on the base, having a 

 pale border below the suture, extending to the apex, and more 

 or less profusely marked with yellow on the caringe, cords and 

 folds of the last whorl. 



The aperture is irregularly ovate, oblique, dark within, but 

 having a bluish-pearly luster; outer lip regularly arcuate, 

 scarcely modified by the carinae. Columella short, concave 

 above, obliquely truncate at the base, covered with a flesh- 

 tinted callus, and bearing a very obliquely descending, thin, 

 spiral lamella. 



Length 33, diam. 19 mm. (Type, A. N. S. P.) 



Length 34.5, diam. 19 mm. (Cooke coll.) 



Kauai : Halemanu and Puukapele (A. Knudsen). 



Amastra knudsenii BALDWIN, Proc. A. N. S. Phila., 1895, p. 

 234, pi. 11, f. 43, 44. Achatinella knudsenii Newc., THWING, 

 Orig. Descriptions, etc., pi. 3, f. 25. 



The type specimen (fig. 4) is a rather thin shell, barely 

 adult. With age the shell becomes thick and heavy. A ge- 



