Original Descriptions of Achatinella. 165 



Remarks. Specimens of this species vary sufficiently in the 

 umbilical region, perhaps, to warrant their separation. Dr. Pfeiffer, 

 the highest possible authority, has founded his species upon what 

 I consider but a variety with a very open umbilicus, of which the 

 figure furnishes a typical illustration. There is, however such a 

 gradation between different specimens with an open umbilicus and 

 those which are closed, that I have not found it possible to draw a 

 line between the two extremes, to determine where one ceases to 

 be my petricola and becomes the typical umbilicata of Dr. Pfeiffer. 



It may not, however, be entirely uninteresting to naturalists 

 to know the reason of the specific name given to this little shell, 

 which, to the author, recalls a scene of thrilling interest. On the 

 Island of Molokai, as on some others of the Hawaiian group, may 

 be found, in the mountain regions, deep gorges inaccessible to 

 man, with precipices of two thousand feet or more, requiring to be 

 scaled to reach the deep, dark, narrow 7 vale which some convul- 

 sion of Nature has opened in the mountain ridge. On such a 

 mountain, so densely covered with bushes four or five feet high, 

 dead specimens of what was at once detected as an unknown species 

 were found. Desirous of obtaining a supply, the writer deter- 

 mined upon making his way over the bushes to an apparent open- 

 ing a few rods distant. In effecting this object, the branches of a 

 friendly tutui tree were seized and used to drag the body forward. 

 The opening was reached, but, to my surprise, my body was pois- 

 ing itself over a precipice, which, to my startled imagination, knew 

 no bottom. Resting on the yielding tops of the bushes, with no 

 support but the friendly tutui branch, the position was one that 

 called for immediate and decided retrograde action, which was, 

 fortunately, effected in safety. On the rocks which formed the 

 upper rim of the precipice some twenty or more specimens were 

 obtained, and no shells in my cabinet have a stronger claim on my 

 affectionate regard than these plain Achatinellae, which live above 

 the clouds on the bushy cliff and along the stony rim of this terri- 

 ble precipice. — Newc. 



Hab. On the rocky sides of a pali or precipice. — Newc. 

 Mapulehu. — Bald. 



293. Achatinella umbilicata Pfeiffer. 



A. {Laminella) umbilicata Pfr. P. Zool. Soc. London, 1855, p. 205. 



A. testa angustissime seel aperte umbilicata, dextr., ovato-conica, tenui, 

 striata, opaca, fusca ; spira convexiusculo-conica, apice acuta; anfr. 6 vix 

 convexiusculis, ultimo spira paulo breviore, basi angulato; apertura elliptica, 

 utrinque angulata, plica colum. compressa, profunda, subtransversa; perist. 

 simplice, acuto, margine colum. subdilatato, omnino libero. 



Shell narrowly but openly umbilicated, dextral, ovate-conic, 

 thin, striated, opaque, brown; spire somewat convexly conic, apex 

 acute; whorls 6 scarcely convex, the last a little shorter than the 



