THE AXLAIAL fJFK OF TIIH r.ROrP. 439 



examples are less than h ({luii'tci- oj' nii inch in dijiiiicliT, tlicy ;n-c seldom taken 

 by other than a specialist witii a taste for collectniu iIk small "pin head" 

 groups of Hawaiian niollusks. 



Occurring in similar localities witli the species mentioned ai)()ve are found 

 the beautiful spiral, translucid. shinin<:' Opeas. A connnon species-" occurs 

 on all the islands, but as there are hut four species belonging to the two genera 

 in the family.-' they are not re-^arded is i!ti|)or1ant. 



The streams, i)articularl\' towards their mouths, ai-e liable to he inhal)ited 

 by one or more of the five or six s])eeies of Xerifliia found in the islands. A 

 large tiat black species with an oi'ange mouth and roughened shell -- is found 

 higher up in certain sti'eams, ailhering to stones. They are gathered for the 

 markets, the finest specimens perhaps coming fi-om Pelekunu Yalley. on Mo- 

 lokai. All of the species are liable to be foiuid on any of the islands, their 

 occurrence apparently depending on the habitat. The several fresh and 

 brackish-water members of this family -■"■ adhere to stones and other objects 

 in the water, and all are eaten l)y the Hawaiians. 



A very common coiled snail shell -^ that grows to he lhi-ee-foui-ths of an 

 inch in diameter, is common all over the island, but especially plentifid about 

 Honolulu, where they occur under boards and flower |)o1s, oi- in moist weather 

 may be found sk^wly creeping about over the grass, fences, walks ami shi-ub- 

 bery. They are the largest representatives of the TTelix family-' in Hawaii. 

 and as this species is widely distributed, it is doubtless an inii'odu<-ed foi'iii. 

 Specimens are abundant in scattered and isolated ]ilaces on Oahn, indicatinL;- 

 that it is by no means a new arrival. 



During a period of drought the animal draws i)ack into the coils of the 

 shell and secretes a whitish paper-like false operculum ovei- the aperture. They 

 will live in this condition for many months, bttt in the rainy season they 

 become active again. 



The curious black slug,-*' about two inches in length with a i)ale line 

 down the center of the back, is also an introduced species that at tinn-s is vei'y 

 plentiful about Honolulu. They are noctui-nal in habit, coming out at inght 

 from moist places where they remain hidden dui'ing the day. Slugs often 

 leave a trail of slime or nnu'ous behind them as they creep along. Tliey are 

 supposed to feed tipon decaying vegetation. Although an iidi"oduced species, it 

 serves very well to represent the family of ti-ue sluizs.-" of which thevo are fivi' 

 or six species known from the inountains on the dilVerenl islands. They are 

 not abundant, however, the most common nati\e slug-'' on ()ahu lie'iig a small 

 species that occasionally occurs in the mountains of Kauai ami ]\raui. 



While the species of several families of Hawaiian sliells'-'' are too minute 

 to be often seen or to admit of a bi'ief cliaraeterizatioti, ihey ai-e. ne\ friiu'less. 

 sure to occur in the matei'ial gathered hy a carci'ul collector. Trobalily be- 

 tween sev(Mit\-ti\-e a!i(l one Inuulred species of lla\\aiian shells ai'c placed in the 



-0 Opeas jiinreus. 21 stfiio(/!/rid(V. "- Xeritina grnnoxn. -^ Xeritid(V. "* F.iilntn sinnhiiis. 



'-° Helividir. ^'^ Yeroiiirelhi sp. -' LimacidtF. ">* A urioliniax bevruoti. 



-" ZoiiifiKlii'. PliiIoi)i[)ridir. E iidodnfid'C. I'liiudiv. Tdrnnti'llitiidip. 



