THE MOIiPHOrOGY OF Tllh) CHEILOSTOMATA. 293 



it is of firmer texture tliau in tlie preceding forms. It has 

 the usual lateral projections of the vertical flange for the 

 insertion of the occlusor muscles. Condyles are barely in- 

 dicated, but they can just be made out as two slight knobs 

 distal to the proximal broadest part of the operculum. 



A Fhistrine series of groups of parietal muscles^ occurs 

 (fig. 0), among which a stronger group {'p. in.') on each side, 

 immediately proximal to the operculum, probably acts as a 

 divaricator, as in Flustra. 



A few of the zooecia are modified as vicarious avicuhiria. 

 The zooccium is normal, but tlie operculum is longer than 

 usual, and the occlusor muscles originate from as much as 

 the distal two thirds of the basal wall. These zooecia are 

 provided with typical parietal muscles. Polypides are 

 absent in most parts of the preparation, but in several cases 

 the vicarious avicularium possesses a polypide. These 

 modified zooecia are not provided with ovicells, which occur, 

 here and there, on the ordinary zooecia. 



Cribrilina radiata, Moll (fig. 7). 



This species, which differs in important respects from C. 

 philomela, is considered in the following section (p. 32(3). 



(c) Lepralioid Genera. 



Under this heading I shall consider not only some of the 

 genera which are usually referred to the Escharina, but a 

 certain number of the branching forms at present included 

 in the Cellularina. 



Umbonula verrucosa,- Esper (fig. 11 ; see also the dia- 

 gram, fig. 12). 



The frontal membrane of this haudsome species is perma- 

 nently Elustrine; but it becomes overarched by a strong 



1 Tlie parietal muscles of Mcin biaii i poicl la iiitida arc ll^M^•e(i \>y Siiiitt 

 (1SG5), pi. vi, ^ll,^ 1; those of C ri briliua fimilarisl)j Jullicii (ISSS), 2, 



(ll. X. 



-• liiucks (ISSOj, p. ol7. 



