1 16 Iiifrodiiction. to Ainmal Morphology . 



only living genus ; these are referred by some to Hydrozoa. 

 3. Thecidae — Palaeozoic ; thick, massive ; tabulce many ; septa 

 not reaching the centre, but uniting peripherally into a dense 

 spurious coenenchyma. 



Sub-order 3. Tubulosa — Palaeozoic corals with a simple 

 pyriform (Pyrgia) or connected (Aulopora) colony with no 

 columella nor tabulae, and striae representing septa, and with 

 an imperforate thcca. In Aulopora the coenenchyma is basal. 



Sub-order 4. Perforata — corals with a porous or netted 

 coenenchyma, with no tabulae, well-developed septa, and 

 rudimental dissepiments ; thecas not costate. This includes 

 the families : — i. JNIadreporidae — compound with thick, simply 

 porous thecae, not distinct from the coenenchyma ; chief radii 

 little or not at all perforated ; two strong septa may reach the 

 middle (Madrepora), or a spongiose columella may exist with 

 closely converging laminae (Eupsammidae). Turbinarina; 

 have six strong septa developed without (Astraeopora), or with 

 a columella (Turbinaria). 2. Poritidas have no lamellar septa, 

 but trabeculoe or bacilli form a netted skeleton ; the calyces 

 may have rudimental dissepiments ; coenenchyma either 

 netted, spongy, separate (Alveopora), or indistinguishable 

 from the calyces (Psammocora), or else rudimental or none 

 (Poritinae). 



Sub-order 5. Aporosa — with an imperforate (except in 

 family 7), compact, lamellar sclerenchyma ; strong, rarely 

 perforate septa ; well developed, often costate thecas ; 

 chambers open for their whole extent, or partly closed by 

 dissepiments or synapticulae ; thecae and septa better deve- 

 loped than in other corals. This includes eight families : — 

 I . Turbinolidae — simple ; multiplying by fission or budding ; 

 no coenenchyma, dissepiments, nor synapticulae (except in 

 Coenocyathus) ; surface granular. A columella may or may 

 not exist, and when present it may be surrounded by one 

 (Caryophyllinae), or many (Trochocyathinas), or no circlets of 

 bacilli. 2. DasmiidK — Eocene corals with each septum made 

 up of three lamella attached to the costate thecae. 3. Stylo- 

 phoridae have abundant loose spinose coenenchyma ; septa 

 large, and costae strong ; central cavity interrupted, not filled 

 by dissepiments ; gemmation irregularly lateral. 4. Oculi- 



