90 University of California Publications in Zoology [ Vou. 14 
Only a few of the samples thus obtained have been subjected to 
quantitative treatment. Later, a series was obtained with the ‘‘ Alba- 
” 
tross’’ improved sampler, a description of which has already been 
given (pp. 15-19). These specimens were retained, until we were pre- 
pared to examine them, in the paraffined pasteboard tubes referred 
to in the description of the apparatus. As in the case of the other 
bottom material, two samples were taken at each point where the 
instrument was used, one being intended primarily for biological 
study, the other for geological or mineralogieal. 
Altogether, material from seventy-nine stations has been subjected 
to the system of examination to be described below. Since from a 
considerable number of stations two or more sections of a tube sample 
have been treated separately, it may be said that one hundred and 
twenty-two bottom samples have been subjected to these analyses. 
These various specimens comprised: (1) dried material. including 
the large stones and much of the gravel, together with the sand from 
certain earlier stations; (2) material preserved in alcohol, including 
most of the sand and much of the mud; and (3) the tube specimens, 
taken with the bottom sampling machines and kept for future study 
in the pasteboard tubes. These last were in all cases composed of mud 
or muddy sand. 
Materials taken in the bag of an ordinary dredge, dragged along 
a course a half mile or more in length, obviously do not represent the 
conditions existing at any single spot upon the bottom. Several quite 
distinct types of bottom deposit may be passed over and scraped up 
in the course of such a haul. Moreover, a sample of this sort will 
contain only materials from a very superficial layer. The specimens 
from the stations between D—5700 and D-—5809 are of this character. 
Materials obtained by means of the ‘‘orange-peel bucket’’ have the 
advantage of being taken from a single restricted spot, and further- 
more of being derived from greater depths. It is impossible, how- 
ever, to obtain stratified samples by means of this instrument. Hence 
it was our practice during the survey to bottle merely a small repre- 
sentative portion of such material, or a mixture derived from several 
points in the mass, in case the latter varied noticeably in appearance. 
The samples from stations D—5816 to 5833 were of this character. 
The tube samples alone furnished specimens which preserved the 
natural stratification of the bottom deposits at points whose positions 
were accurately known. All of the samples from the hydrographic 
