262 PARTULA, SAMOAN ISLANDS. 



IV. PARTITIVE OF THE SAMOAN ISLANDS. 



The Samoan Partulae are still very imperfectly known, 

 species having been collected only on Upolu and Tutuila. 

 Nothing is known of the species of the largest island, Savii, 

 if any exist there, or of several smaller islands of the group. 



The known forms belong to four groups, quite diverse in 

 texture and coloration, but two of them are alike in having 

 the umbilicus unusually open. 



Key to Samoan species. 

 a. Umbilicus or rimation very broadly open. 



b. Shell covered with a greenish-yellow or chestnut 

 cuticle; whorls 5 to 5%. 



c. Last whorl spirally striate throughout. 

 d. Dextral. 



e. Length 21, diam. 14 mm. 



P. abbreviata, no. 56. 

 ee. Length 22 x 13 to 25 x 14 mm. 



P. stevensoniana, no. 55. 

 dd. Sinistral; greenish-yellow with pale 

 spire. P. conica, no. 54. 



cc. Later whorls without spiral striae except at 

 the base of the last whorl ; spire dark-colored. 

 d. Last whorl swollen at base; umbilicus 

 ample. P. canalis, no. 53. 



dd. Last whorl tapering downward ; umbili- 

 cus narrower. P. c. biconica, no. 53a. 

 bb. Shell mottled or streaked with, opaque white or buff 

 on a corneous gray or brown ground, or maculate 

 with gray or brown on a pale ground; whorls 4 

 to 4y 2 . 



c. Last whorl very wide, not striate spirally; 



umbilicus deep. P. expansa, no. 58. 



cc. Last whorl spirally striate ; shell oblong-conic, 

 rimate. 



d. Aperture smaller. P. zebrina, no. 57. 

 dd. Aperture larger. 



P. z. recluziana, no. 57&. 



