I20 Introduction to Animal Morphology. 



lated ccenosarc, with large external spicules, and sub-cylin- 

 drical incurved polyp-cells ; Paralcyonium is membranous, 

 branched, with large dermal spicules at the base, the somatic 

 cavities opening freely into each other. 



Order 2. Tubiporacese (organ-pipe corals of the 

 Indian Ocean) — sclerobasis none ; the purple-red 

 epitheca is tubular, made of consolidated spicules 

 ( Wright) ; the tubes are united by table-like, calcified, 

 perithecal dissepiments, from which new tubes bud ; 

 the eight green tentacles have oval lenticular spicules ; 

 the central mouth has a circular lip. On irritation, the 

 tentacles first close together, then the whole polyps 

 sinks into the tube. The stomach has delicate walls, 

 ex. Tubipora. 



Order 3. Pennatulacese (sea-pens) — sclerobase soft, 

 free-swimming, or sand-embedded, of calcified, horny 

 matter, traversed by soft radial bands. The lower 

 part of this axis is barren ; the upper, or pars polypi- 

 fera, is variably branched, and its ectoderm is spiculi- 

 gerous (except in Halisceptrum and Lygus).* Three 

 kinds of zooids may exist: — i. Nutritive, tentaculate. 

 2. Sexual, non-tentaculate. 3. Rudimental, neither 

 sexual nor tentaculate. 



There are three families : — i. Pennatulidae — feather-shaped 

 colonies ; polyps along the margins of the pinnately-branched 

 axis ; pars polypifera bilaterally symmetrical. In these, the 

 principal zooids may reach the fleshy pinnae, and the spicules 

 may be fascicular (Pteroides), or the zooids are on the ventral 

 side of the rachis, with the spicules scattered (Pennatula), or 

 none (Halisceptrum, Sceptonidium). The pars polypifera 

 may be narrow, and the pinnae short, with no spicules 

 (Virgularia, Lygus), or with a spicular plate below the pinnae 

 (Stylatura) ; or the zooids may be on a thick ridge of the 



* Richiardi gives the name Zoanthodema to the ccenosarc. 



