THE PELAGIC FAUNA AND FLORA. 195 
the Tortugas, where numerous patches of them gave a reddish 
color to the sea. 
The siliceous types of Polycistine (Fig. 120), so common in 
former geological times in the West Indies, form an extensive 
deposit at the Barbados, near the highest part of the island, 
are now found but rarely in the Atlantic. A few types of the 
Fig. 120. — Pterocanium charvbdeum. Highly су 
magnified. (Miiller.) Fig. 129. — Sphsrozoum. 1, 
Thalassicole (Fig. 121), and Acanthometridz, as well as of 
such forms as Collozoum and Spherozoum (Fig. 122), are, how- 
ever, quite common in the Gulf of Mexico and Caribbean, and 
during the summer come as far north as the larger pelagic 
animals. Siliceous radiolarians are quite common in the tropi- 
cal regions of the Pacific. 
While many of the foraminifera, like Globigerina and Has- 
1 Nummulitie beds occur in Thibet at a height of sixteen thousand feet. 
