246 PARTULA, RAIATEA AND TAHAA. 



pale yellow or brownish yellow, typically with a narrow 

 brown band revolving a short distance below the suture, and 

 a wider one just below the perifery; but sometimes the 

 whole base is dark chestnut, or the whole shell may be dark 

 except for a light equatorial girdle or zone. The aperture is 

 nearly white inside, lip broad, white, well expanded and 

 strongly thickened within. The columellar lip bears on its 

 inner face a low nodule, sometimes hardly noticeable. The 

 parietal tooth is deeply placed and well developed. 



Length 20%, diam. 13 mm. (fig. 8). 



Length 18, diam. 12 mm. (Pease). 



Tahaa, confined to Faa-apa valley on the east coast, where 

 it O'ccurs in abundance on the trunks of a species of wild 

 banana and at the roots of ferns. (Garrett). 



Partula bilineata PEASE, Amer. Jour. Conch., ii, 1866, p. 

 201 ; 1867, p. 81, pi. 1, fig. 10 ; Proc. Zool. Soc., 1871, p. 473. 

 BINNEY, Proc. Acad. Nat. Sci. Phila., 1875, pp. 245, 247, 

 pi. 19, fig. 10 (anatomy). PFEIFFER, Mon. Hel., viii, p. 195. 

 SCHMELTZ, Cat. Mus. Godeff., vi, p. 81. HARTMAN, Cat. 

 Part., p. 8; Obs. Gen. Part., Bull. Mus. Comp. Zool., ix, pp. 

 180, 196. GARRETT, Journ. A. N. S. Phila. ix, 1884, p. 62. 



P. plamlabrum is more lengthened and less glossy than 

 bilineata, and the two have not the same cycles of color-forms. 

 P. umbilicata is a still more shortened and globose form. 

 These three species of Tahaa are slight modifications of the 

 ancestral Raiatean P. auriculata stock. Fig. 14 represents 

 Pease's type specimen. Garrett writes of P. bilineata: "It 

 is readily distinguished by its smooth, glossy surface, ovate- 

 conic form, yellowish horn-color, and two revolving chestnut- 

 brown bands, the upper one narrow and subsutural. The 

 subacute apex is sometimes purple-brown and the suture is 

 margined by a narrow, rugose, whitish line. The constant 

 parietal tooth is prominent and the broad white peristome 

 is slightly emarginate above, strongly labiate within, and 

 widely expanded. 



Var. a. With a single broad median chestnut-brown band. 

 Not common. 



