12 Trans, Acad. Sci. of St. Louts 
TEREDO (ZOPOTEREDO) FULLERI* SP. NOV. 
Plate III, figs. 16-22. 
Shell subglobular, small, bluish white, covered with a 
strong, transparent periostracum. <A thin, broadly 
curved, incised line separating the anterior from the 
anterior-median area. The angle formed by the ventral 
ridges of the anterior area with the anterior rows of the 
anterior-median area, considerably more than 100°. 
Externally, the anterior area, large. In height, slightly 
less than half that of the entire shell. The denticulate 
ridges of this area twice as wide as the spaces between 
them. There are in the vicinity of the ventral edge about 
twenty-five of these ridges to the millimeter, each ridge 
bearing one hundred and thirty minute denticles to the 
millimeter (fig. 16). In the type specimen, the anterior- 
median area at its widest part is one-half of the width of 
the entire median area and bears thirty-six closely 
crowded denticulate ridges averaging, in 4 line contin- 
uous with the ventral edge of the anterior area, forty 
teeth to the millimeter. Each ridge bears closely 
crowded, nearly square, denticles, there being forty-five 
of these denticles to the millimeter (fig. 17). The 
middle-median area is narrow, translucent, with the ven- 
tral ends of the ridges of the anterior-median area dis- 
appearing quickly or persisting only as faint growth 
lines. The posterior-median area opaque, milk-white, 
smooth, except for microscopic incised growth lines. The 
auricle small, not clearly separated from the posterior- 
median area, the dorsal edge concave. 
Internally, a large, sharp, curved hinge-plate in the 
left valve. The blade two-thirds of the length of the 
*] have named this species for Mr. Nelson M,. Fuller, of the Massa-~- 
chusetts Institute of Technology, in recognition of the assistance he 
has given me in the study of the shipworm problem. 
