66 



SHELL GALLBKY. 



Case B 1. succeeding layers of cells. The Reteporidce, (Case B 1) form delicate 

 stony networks. The reticulate fronds may be expanded out, or 

 may form tubular or contorted growths (Fig. 15, Retepora leaniana). 

 The beautiful Retepora phmnkm 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 GatenicellidcB 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, Gatenicella ventrkosa). 



Fig. 16. 



Gatenicella ventricosa. A, natural size ; B, magnified. (After Busk.) 



Case B 2, Sab-order 2. — Ctenostomata, 



and A 



upright The Ctenostomata are fleshy, horny, or membranous ; never 



P*'*' calcareous. When the tentacles of a polypide are retracted into 



