SPONGES. 171 
CHARACTERISTIC DEEP-SEA TYPES. 
of certain species was often very great, yet the continental fauna 
of that region is poor when compared with the wealth of species 
found in the Caribbean Sea and Gulf of Mexico. 
Among the Hexactinellide one of the most common types is 
he E : 
Fig. 520. — Farrea facunda. 2. 
the variable Farrea facunda (Fig. 520), which oceurs either as 
a simple or a somewhat complicated form ; it is found at depths 
Fig. 521. — Lefroyella decora. $. 
of 300 to 1,000 fathoms. One of the finest, figured by Thom- 
son, a species called Lefroyella decora (Fig. 521), was dredged 
