51 



stratum. Bones of all vertebrates, except very rarely those of fish, seemed 

 totally absent in this sti'atum. 



Shells were not sufficiently abundant to modify the appearance of the 

 layer, which was totally free from any admixture of earth or extraneous 

 matter, and presented the aspect, until closely examined, of fine, pure, uni- 

 form, greenish-white sand. This bed varied in thickness from a total of two 

 feet to three feet in a vertical direction. The deposit extended everywhere 

 underneath the shell-heaps, covering an area of three acres and a half at 

 Attn, about four and three-quarters acres at one of the Amchitka vil- 

 lages, and at Adakh half an acre or more, by measurement. Traces of it 

 were found in all the shell-heaps examined, though its depth and extent 

 were less fully determined at other points than those above mentioned. 



The echinus, though possessing no edible tissues of its own, is furnished 

 with ovaries on the inner side of the dome of the test, radiating from the 

 center. These, when in full condition, which occm-s in some individuals at 

 all seasons of the year, offer two or three tablespoonfuls of really palatable 

 minute eggs, tasting like an oyster, and of a bright-yellow color. It would 

 require forty or fifty adult individuals to afford a good meal for a man. 

 They are eaten to this day in a raw state by the Aleuts. We may arrive at 

 some slight idea of the length of time it must have taken to have formed 

 such enormous deposits of this material, by a simple calculation. It is not 

 at all likely that a community of natives could constantly obtain a sufficient 

 supply of this kind of food at any one locality for any great length of time 

 continuously. It is probable that they migrated from place to place within 

 a certain area, subsisting at one place vuitil the supply became short, and 

 then going to another, and so on until the original locality had become 

 restocked, which might readily occur, such is the abundance of this animal, 

 in two or thi-ee months. It is also probable that at some seasons other kinds 

 of food might be resorted to, such as birds' eggs in the spring, &c. We 

 may suppose that one locality might supply them with echini for three 

 months of the year, at different periods during the year. It is j^robable, 

 also, that at that time, with the limited amount of food to be obtained, the 

 communities woiild be small, probably not exceeding twenty persons each 

 on the average. 



