66 SHELL GALLERY. 
Case B l. succeeding layers of cells. The Reteporida (Case B 1) form delicate 
stony networks. The reticulate fronds may be expanded out, or 
may form tubular or contorted growths (Fig. 15, Retepora teaniand). 
The beautiful Retepora phamicea from Torres Straits is of a rich 
purple colour. 
The Adeonidce form thick fenestrated plates which unite to form 
cavernous masses usually attached to rocks by a thick jointed 
stem. Several very fine examples from Port Phillip, Victoria, are 
exhibited in the upright part of Case B. 
Case A 2. The CatenicellidcB are represented by a fine series of specimens 
from Australia. The colonies form dense clusters of finely beaded 
branches. The cells are arranged in single series, each cell being 
united to those above and below by a horny joint. The cells are 
usually urn- shaped with a triangular avicularium at each upper 
angle, and with the front surface variously sculptured with pores or 
bands (Fig. 16, Catenicella ventricosa). 
Fig. 16. 
Catenicella ventricosa. A, natural size ; B, magnified. (After Busk.) 
Case B 2, Sub-order 2. — Ctenostomata. 
and A 
upright The Ctenostomata are fleshy, horny, or membranous; never 
part. calcareous. When the tentacles of a polypide are retracted into 
