THE ANLMAL LIFE OF THE GROUP. 439 



examples are less than a quarter of an inch in diameter, they are seldom taken 

 by other than a specialist with a taste for collecting the small "pin head" 

 groups of Hawaiian mollusks. 



Occurring in similar localities with the species mentioned above are found 

 the beautiful spiral, translucid, shining Opeas. A common species-" occurs 

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

 in the family,-^ they are not regarded is important. 



The streams, particularly towards their mouths, are liable to be inhabited 

 by one or more of the five or six species of Xeritiiia found in the islands. A 

 large flat black species with an orange mouth and roughened shell -- is found 

 higher up in certain streams, adhering to stones. They are gathered for the 

 markets, the finest specimens perhaps coming from Pelekunu Valley, on ^Mo- 

 lokai. All of the species are liable to be found im 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 by the Hawaiiaus. 



A very common coiled snail shell-* that grows to be three-fourths of an 

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

 Honolulu, where they occur under boanls and flower pots, or in moist weather 

 may be found slowly creeping about over the grass, fences, walks and shrub- 

 bci-y. They are the largest representatives of the Helix f amily ^s in Hawaii, 

 and as this species is widel.\' distributed, it is doubtless an introduced form. 

 Specimens are abundant in scattered and isolatrd places on Oahu. indiratinu- 

 that it is by no means a new arrival. 



During a period of drought the aninud draws tiack into the coils of the 

 shell and secretes a whitish paper-like false operculum over the ai)erture. They 

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

 become active again. 



The curious black slug.-" about two inches in length with a pale line 

 down the center of the back, is also an introduced species that at times is very 

 plentiful about Honolulu. They are nocturnal in habit, coming out at night 

 from moist places where they remain hidden during the day. Slugs often 

 leave a trail of slime or mucous behind them as they creep along. They are 

 supposed to feed upon decaying vegetation. Although an introduced species, it 

 serves very well to represent the family of true slugs,-" of which there are five 

 or six species known from the mountains on the different islands. The.v are 

 not abundant, however, the most common native slug-'* on Oahu being a small 

 species that occasionally occurs in the mountains of Kauai and Maui. 



While the species of several families of Hawaiian shells-* are too minute 

 to be often seen or to admit of a brief characterization, they are, nevertheless, 

 sure to occur in the material gathered by a careful collector. Probably be- 

 tween sevent,\-fi\e and one hundred species of Hawaiian shells are placed in the 



-" Opens junceus. " Stenoyuridce. -- Neritina grnnom. -' Neritida. -^Eiilnln siniilaris. 



-" Helirida'. -■* Veronicella sp. -' Limacidw. -^ Apriolimax bevenoti. 



-' Zonitttdte. PhUomiieidw. Endodotidm. Fupidie. TornciteUinid<e. 



