PLANAMASTBA. 131 



surface of the last whorl; slightly shining. Embryonic 

 whorls apparently I 1 /?, weakly convex, faintly marked with 

 growth-striae and on the latter part having a few delicate 

 spiral raised lines and some very fine radial wrinkling. The 

 next whorl is moderately convex, with sculpture of faint 

 growth-lines and very minute, retractive corrugations, more 

 oblique than the growth-lines. The last half whorl is rather 

 coarsely, irregularly wrinkle-striate, and microscopically 

 granulose. The base has irregular growth-lines., but very 

 little microscopic sculpture. Whorls 3, the last acutely 

 carinate at the periphery, convex below, very obtusely sub- 

 angular near the umbilicus. Umbilicus extremely shallow 

 and open, showing 2y 2 convex whorls. Aperture somewhat 

 oblique the outer and basal margins of the peristome sim- 

 ple and sharp, columellar margin but slightly dilated, thin, 

 unarmed. Alt. 1.7, diam. 4.9 mm. 



Hawaiian Is. (Pease). Type 1984 coll. A. N. S. P. 



Very unlike P. digonophora by its microscopic sculpture, 

 more convex whorls, pale color with a band on the last whorl, 

 and the very shallow umbilicus; yet I can find no other 

 genus which would contain this snail. It may possibly be 

 the Helix depressiformis of Pease, but in the collection of 

 the Academy it was labelled "H. alata," and Pease makes no 

 mention of a band on his species. 



P. depressiformis (Pease). 



"Shell discoidal, planorboid, planulate above, convex be- 

 neath, thin, subpellucid, a little shining, brownish-corneous, 

 broadly umbilicate, obliquely closely rugose-striate. Spire 

 planulate, sometimes a little elevated. Whorls 3y 2 , slightly 

 marginate, the last acutely carinate, at the margin compressed 

 roundly carinated at the umbilicus. Alt. 2, diam. 7 mm." 

 (Pease). 



Islands of the Central Pacific (Pease). 



Helix depressiformis PSE., Proc. Zool. Soc. London 1864, 

 p. 670, no. 8. 



This species and the next were apparently based upon 

 forms of Planamastra. Both were described from the "Cen- 



