HFNSHAW: SF.MI-FOSSIL SHELLS IN HAMAKUA DISTRICT, HAWAII. 57 



Much of the coast Hne of Hamakua is very precipitous, especially near 

 Waipio \' alley, the cliffs there lising sheer to a height of 600—800 feet. 

 Formerly no doubt the forest extended clear to the brink of the cliffs, but 

 for many ^•ears past waving sugar cane has usurped the place of the forest, 

 ever creeping steadily upwards, until now the cane fields have reached a 

 final limit of about 1,800 feet. 



Above the present limit of the cane is a belt of forest. Most of this has 

 t)een fenced from cattle for the past twenty years to preserve the water supply, 

 and in many places the land is as densely covered as it ever was with kukui, 

 ohias, and with the usual variety of ferns, shrubs and plants that go to make 

 up the Hawaiian forest. As rare inhabitants of the depth of this forest, but 

 more abundant on its edges and in the partial openings, are found Siircmea 

 iwonspinia, Ancey, 'S'. hirolorafa, Ancey, aS'. liulinsii, Ancey, one or two 

 others of the genus and a number of the minute species of land shells. 



There are portions of this forest-belt where the timber is very thin, and 

 here live on the ahakea {Bohea elatior. Gaud.), the ohias {Meffo><i(lero>< 

 jtolijinorjtha, Gaud.), and the koolea trees {Mijrsine Jisseiiiana, A. D. C.), the 

 Achafinclla horit/-i-i^ Baldw., and the A. hairaiien^i-^, Baldw., species which 

 seem to wholly shun tlie dense forest and inhabit only isolated trees where 

 light and warmth abound. 'J'his open forest section has been invaded by the 

 all-conqering " Hilo grass '' (Patjalum conjut/afnm) which apparently is des- 

 tined to materially affect the future of both tlie forest and the shells. It 

 grows here most luxuriantly in a dense mass which effectually screens the 

 earth from the life-giving sun, and smothers in its embrace all the seeds that 

 fall from the trees above. To the presence of this grass in the open district 

 , here described, I attribute the fact, that, though fenced from cattle, there are 

 absolutely no young trees coming forward, the probable result being the 

 extinction, in the not distant future, of the trees and the shells inhabiting 

 them. 



Above the timbered belt just mentioned, and distant from the sea some 

 six miles, are the so-called Waimea Plains. To the north and west are the 

 Kohala mountains, which rise to the height of about 8,000 feet. 



To-day the plains are almost entirely treeless, except here and there 

 for scattered pua trees which form the home of the Arhafinella pliysa. 

 There still stand, however, many skeleton trunks of the ohia and koa trees, 

 whose naked and broken branches like outstretched arms, seem raised in 

 protest against the fate that has overtaken them and and their fellows lying 

 on the ground. Less than fifty years ago it is said to have been impossible 

 to ride anywhere over the present plains except by trails because of the 

 multitude of fallen tree trunks that everywhere blocked the way. This 

 brings the forest down to comparatively recent times, and there is no reason 

 to doubt the generally received tradition that a century ago the present plains 

 were covered with an impassably dense forest, a fact essential to remember 

 in connection with the fossil remains to be described presently. 



