148 A, E. Verrill—The Bermuda Islands; Geology. 
Another large species (Cirratulus grandis) is olive-green or yel- 
lowish brown, with numerous long reddish cirri (fig. 42). The large 
Pectinaria regalis, which constructs a remarkable portable, cornu- 
copia-shaped tube of shell-sand, the particles regularly cemented in 
a single layer, is common.* Many smaller species, with similar feed- 
ing habits, are abundant in the mud and sand, and must make large 
contributions to the deposits of fine materials. 
Many species of crabs found there, and also other crustaceans, 
feed largely on small mollusks, usually crushing the shells with 
Figure 42.—Cirratulus grandis V., nat. size. Drawn from life by A. E. Verrill. 
their strong claws, thus contributing to the shell-sand. Many of the 
univalve mollusks (Gastropoda) feed on bivalves, usually drilling 
a hole in the shell through which they suck the blood. The well- 
known “drill,” which is so destructive to young oysters on the 
American coast, is a good example. Many related species with 
similar habits are found in Bermuda. There are also many fishes, 
abundant there, that feed on small mollusca and other calcareous 
bottom organisms and thus contribute to the formation of the fine 
mud. 
* These Trans., vol. xi, p. 38, pl. viii, figs. 6, 7, 1901. 
