1879.] 239 [Kneeland. 
guano deposit, nearly even, though the hard coral bottom of the 
bed slopes toward the centre, the depth of the guano varying from 
one-half'to several feet. There is little vegetation and few trees; 
the lagoon is very shallow, containing no growing coral; its shores 
are of coral mud, which allows the foot to sink into it eight to ten 
inches, rendering it difficult to reach its waters; the mud looks like a 
dirty brownish clay, but is nothing but very finely comminuted coral; 
the water of the lagoon is occasionally salt, and its shores are in 
some places incrusted with salt. 
The climate is equable, the temperature ranging from 76° to 80° 
Fahr., in the shade; easterly trade winds are constant, in summer 
with northing, in winter with southing; sky usually clear and cloud- 
less; light showers are not uncommon, though heavy ones are un- 
known, and there is never a rainy day. There are no mammals 
on the island except rats, which feed on eggs; it is occasionally 
visited by turtles, and by civilized man; and it is not unlikely that 
bones of various marine animals may occur in the deposit, and I 
think some of the specimens afford evidence of this. As there is no 
fresh water upon the island except what is caught during rains, and 
no food to depend upon except fish, birds, and their eggs, vessels em- 
ployed in collecting the guano have to carry their own supplies, 
causing considerable privation when from baffling winds supplies fail 
to reach them in proper time. 
The birds most abundant here are the tern (Sterna hirundo), which 
comes in millions twice a year to breed, resting on the ground, mak- 
ing no nest, but getting under tufts of grass where any exist — nod- 
dies, (Anous stolidus), which burrow in the guano, — boobies and 
gannets (Sula fiber and bassana) great devourers of fish, which they 
disgorge when feeding their young or when alarmed — petrels 
(Procellaria), tropic birds (Phaeton), and frigate birds (Tachypetes) 
— all of these contribute to the formation of the guano. 
There are several varieties of this mineralized guano, differing in 
the amount of the phosphates contained. 
1. A sandy or granular kind without ammonical odor, of which 
the average composition, from another locality, according to Dr. A. A. 
far as Hayes is, as the salts of lime are concerned: 
Bone Phosphate of Lime : ; 46.60 
Carb. of Lime . : : A 39.80 
Organic Matters . 5 é : 6.40 
