12 BUREAU OF AMERICAN ETHNOLOGY [Bull. 177 
various times to all four of the plain wares. Such a subdivision 
would reveal the same trends as the plain wares themselves show, 
however, and while obscuring any change in popularity of the decora- 
tive techniques and motifs. It might have been possible in a few 
cases to subdivide decorated types on the basis of differences in motif, 
but when the technique was uniform and the sample was small we 
preferred to consider the complex as a single type characterized by 
the presence of several motifs. When some evolutionary change can 
be detected, this is mentioned in each pottery type description under 
the heading, “Temporal differences within the type.” In contrast to 
the plain wares, decorated types rarely show any clear-cut changes 
in popularity in cultures of the level of development represented by 
the archeological phases in the Tropical Forest area of South Ameri- 
ca. Consequently, this test of classificatory validity does not apply, 
and the principal consideration becomes one of separating combina- 
tions of technique and motif that appear to have some descriptive 
unity. 
The adoption of this philosophy of pottery type classification inevi- 
tably colors our approach to the discrimination of archeological 
phases. The ceramic complexes by which the phases are principally 
identified are composed of continuously changing pottery types. 
These changes may be either evolutionary or the effect of outside in- 
fluence, but in either case the alteration is usually slow. Such a point 
of view emphasizes the continuum rather than the innovations, and 
makes subdivision of a phase seem exceedingly arbitrary or even un- 
realistic. While the combination of traits at the end of a phase 
sequence may be easy to distinguish from that at the beginning, the 
transition from one to the other is very gradual. This orientation 
should be kept in mind when our descriptions of the British Guiana 
archeological phases are compared with the styles distinguished by 
Cruxent and Rouse (1959) for eastern Venezuela. These authors 
have followed another approach, which emphasizes differences rather 
than similarities, with the consequence that a sequence of change such 
as that encompassed within our Mabaruma Phase, for example, may 
be represented by two or more styles in their scheme. It should be 
recognized that this is not a situation in which one result is neces- 
sarily right and the other wrong, but a consequence of approaching 
similar data from different theoretical premises. 
Several devices for recording and presenting archeological evidence 
that we use consistently appear in this report. An archeological cul- 
ture has been called a “Phase” because this term carries no specific 
ethnographic connotations (see Meggers and Evans, 1957, pp. 138-14). 
All sites are designated by a key letter and number, the letter referring 
to the geographical area in which the site is located (N=Northwest 
