A, EF. Verrill—The Bermuda Islands; Geology. 139 
bivalves are in excess of the univalves, thongh more of the latter are 
entire.* (See figures 34a, 346, and pl. xxiv, figs. 1, 2.) 
Part of the small shells are the young of larger species, but the 
greater number never grow large. Such small species (pl. xxiv) are 
probably annual, or at most biennial, and reproduce rapidly, so that 
34a. 
34d. 
Figure 34a.—Washed shell-sand from off Bailey Bay, in 4 fathoms. x1¥%. 
Figure 34b.—Washed shell-sand from main Ship Channel, in 6 fathoms. x 11¢. 
their total increase in bulk is greater than that of larger shells with 
slower rates of growth and reproduction. But fragments of larger 
shells are also found in considerable numbers in most samples, espe- 
cially in those from the shores and very shallow waters. 
In many localities, near the reefs and rocks, fragments of Verme- 
tus and allied genera occur in considerable quantity. One of these, 
Tenagodus, or Siliquaria, ruber, is red and often imparts a reddish 
tint to the sand. In other cases the reddish tint is due mostly to 
fragments of Spondylus, Tellina and Chama, and to the sessile fora- 
minifer, Polytrema miniaceum, which is common on dead corals. 
In nearly all the samples of fine sand a very small percentage of 
diatoms, spicules of gorgoniz-and of sponges, and shells of ostra- 
codes could be found, and also, occasionally, a few radiolarians, but 
such organisms collectively would usually not make up a tenth of 
one per cent. of the material. 
Fragments of corallines, or calcareous algze, of the genera [Hali- 
meda, Udotea, Lithothamnion, ete., are usually common, especially 
near the reefs, and often form an important element. Foraminifera 
* Numerous species of these small shells were described and figured by Ver- 
rill and Bush,—these Trans., vol. x, pp. 513-544, pls. Ixiii-lxv, 1900; and ‘‘ The 
Zoélogy of Bermuda,” article 3, reprint. 
