Systematic Part. 



Order Cheilostomata. 



The zoacia, to a larger or smaller extent calcified, as a rule furnished with 

 an operculum (except Bugula). There can he found four different forms of indi- 

 viduals: uulozoa-cia, heterozooecia, gonozoa-cia and kenozooccia, and in many cases 

 the eggs are matured in special, outer or inner, calcareous marsupia, the so-called 

 ooecia. The separating walls between the individual zocecia are furnished with 

 rosette-plates, and in colonies consisting of more rows we can as a rule distin- 

 guish between a horizontal or oblique distal wall and vertical lateral walls, 

 which are most frequently independent. More rarely a lateral wall is common 

 to two adjoining zocecia, which on the other hand is almost always the case with 

 the distal wall. 



Suborder Anasca. 



A compensation-sac is wanting, and the frontal wall is either wholly or in 

 part membranaceous, or calcareous, depressed and surrounded by raised margins. 

 In the heterozoa'cia the opercular and the subopercular areas are as a rule not 

 separated by a continous calcareous bar, but only partially by the hinge-teeth 

 of the operculum. 



1st Division: iVlalacostega. 



The individual zoa-cia are plainly marked olf on the surface of the colony. 

 The frontal wall quite or partially uncalcified and the operculum as a rule a 

 membranous valve, the rim of which is chitinized, but which proximally passes 

 over into the frontal membrane. 



