1895.] NATURAL, SCIENCES OF PHILADELPHIA. 225 



There occurs also a pure white form of the shell without the 

 peripheral band, and a form white with a light chestnut band on the 

 apical whorls. The animals of these varieties vary only a trifle 

 from that of the typical form. 



This species belongs to the group of A. physa Newc, but is 

 easily distinguished by its much more inflated body whorl and 

 smaller spire, its smoother and polished surface. The habitats of 

 the two species are widely separated, and the animals are entirely 

 different. The animal of A. physa, mantle and fuot, is a dingy 

 white with a greenish yellow tinge. 



We dedicate the species to Mr. J. Lewis Horner, the young natural- 

 ist to whom science is indebted for the discovery of this and the fol- 

 lowing species. They are valuable additions to the shells of the 

 Island of Hawaii, which has heretofore furnished only one described 

 arboreal species of Achatinella. 



Aohatinella Hawaiiensis, n. sp. PI. X, figs. 24, 25, 26. 



Shell sinistral, minutely perforated, very thin, acutely conical, 

 apex acute ; surface rather lusterless, covered with fine lines of 

 growth, and under a lens showing extremely close and delicate de- 

 cussating spiral lines ; nuclear whorls faintly decussated. Color 

 very variable, plain brown or dingy white, sometimes irregularly 

 striped or mottled with brown and white, the base generally uniform 

 brown, but sometimes with undulating markings of brown and 

 white ; the only constant characters being a brown, sometimes inter- 

 rupted, line at the periphery, bordered below with a broader white 

 line. Whorls 6, slightly convex, the last inflated. Suture lightly 

 impressed. 



Aperture oblique, oval, brown, the peripheral brown and white 

 bands distinctly marked within. Peristome acute, not thickened 

 within, external margin straight, basal expanded, the expanded 

 portion being very thin and fragile, the columella margin reflexed 

 over the minute perforation ; color white on both face and the 

 reverse. Columella white, very slightly developed, plain and 

 smooth. 



Length, 18 ; diam. IO2 mm. 



Habitat, Hamakua, Island of Hawaii. 



Animal when extended in motion longer than the shell. Mantle 

 almost white, margin of a darker shade. Foot above and below 



