62 BUREAU OF AMERICAN ETHNOLOGY _ [Bull. 177 
Analysis of the shellfish species composing the midden refuse is not 
conclusive, but there is some evidence to suggest that a dietary change 
was taking place. In addition to crabs, fish, and occasional mammals 
and birds, six types of shellfish were eaten by people of the Alaka 
Phase: two species of snails (Veritina zebra Bruguiére and Thais 
coronata) Lamarck), a brackish-water mussel (A/ytilus falcatus 
Orbigny), a mangrove oyster (Crassostrea rhizophorae Guilding), an 
intertidal clam (Phacoides pectinatus Gmelin), and a marine or 
brackish-water conch (Melongena melongena Linné). However, not 
all these species occur at all sites, and when the sites are grouped in 
the order indicated by the pottery and stone artifact analysis (table 
B), the result shows that four species occur throughout the sequence 
but two others were exploited only at the early sites (table C). Geo- 
graphical distribution will not account for this difference since N-9 
is in the vicinity of N-8 and N-10. The alternative explanation that 
the two species are absent from the later sites because they became 
extinct owing to overharvesting by the Alaka Phase peoples does not 
receive support from either malacologists or archeologists, since these 
two species were not eaten in any greater quantity than the ones that 
continued to thrive and be eaten. In view of these factors, it seems 
probable that the decrease in the variety of shellfish exploited is 
related to an addition of other kinds of food to the diet. 
TABLE C.—Distribution of shellfish species at Alaka Phase sites 
Species of — 
Site | 
Melon- Thais | Neritina |Phacoides| Mytilus | Crassos- 
gena trea 
INSYS Stat sotto. Pee eee eh cee een ose A eal eet ee be x x Xx x 
NEG siesenteboot tote cle aeecee tuesatelovonebose LB ces aos x x x x 
DN Fes [ee ee a ee es See ol eee | |e ee hm, Meee ee Moyo | Jscee yee eee x 
N=Si Ee. os Aue eee ae eS x x x x paisa (pi it Pe sae 
N=10 es 2h be ee sede. ee 4 x x > S| PoP er eee Eterna x 
SYS EES SP se al sg i ra Se! Spee a ae x x OS Wy) SES Sees’ 
In addition to a decline in the number of species utilized, there 
is a notable decline in the density of the shell refuse in the late sites, 
particularly in N-11 and N-16. N-11 is somewhat unique because of 
the disturbance it has suffered from drainage and cultivation, but if 
the shell refuse had ever been as densely compacted and cemented 
together as in the earlier sites the disturbance would have had to be 
greater than it is to destroy this evidence. At N-16 the shells are 
loosely mixed with dirt and other refuse in a manner similar to that 
at N-11. In the four earlier sites, by contrast, shell was very con- 
centrated, with little dirt intermixture. Percolating water produced 
chemical action in which lime was dissolved and redeposited, resulting 
