78 



THREE CRUISES OF THE " BLAKE. 



F.RYOZOA. 



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- 



culata. -?. 



Fig. 324. Diastopora Fig. 325. Fareiminaria 



repens. 



1. 



delicatissima. 4 (Busk.) 



i- 



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 



I 



Fig. 323 o. Crisia denti- 

 culata. Magnified. (Sniit.t. ) 



Fig. 324 a. Diastopora repens. 

 Magnified. (Smitt.) 



thus becomes most difficult, without a full Fi 3250. 

 knowled^e of the entire development, to char- narfa delic 



' *- n T i i / T"k 1 \ 



n . .. .. Magnified, (ousk.) 



acterize a species and assign it to its true 



family or genus. Among the bryozoa, more than three quarters 



