THREE CRUISES OF THE “BLAKE.” 
BRYOZOA. 
In the study of no group is abundant material more necessary 
than in that of the bryozoans. 
In the majority of animals, we are accustomed to look at dif- 
Fig. 323. — Crisia denti- Fig. 324, — Diastopora Fig. 325. — Farciminaria 
culata, 2, repens. 1. delicatissima. 4. (Busk.) 
ferences due to growth as transitory, and we define species from 
their full-grown stages; but in the bryozoans the differences of 
growth are persistent in the individuals of the 
colony, while they may propagate at very dif- 
ferent stages of the colonial development. It 
Fig. 323 a. — Crisia denti- Fig. 324 a. — Diastopora repens. 
culata. Magnified. (Smitt.) Magnified. (Smitt.) 
thus becomes most difficult, without a full Fig. 325 a. — Farcimi- 
knowledge of the entire development, to char- naria delicatissima. 
‘ è i . . Magnified. (Busk.) 
acterize a species and assign it to its true 
family or genus. Among the bryozoa, more than three quarters 
