Introduction to Animal Morphology. 1 1 9 



somatic cavities of the polyps extend into the coeno- 

 sarc as a communicating tubular system, into which 

 the mesenteric folds extend. The sex organs develop 

 on these, as in Zoantharia, and craspeda are often 

 present. 



Three families are contained: i. Cornulariido? rarely 

 simple (Haimeia with retractile polyps and a simple tube ; 

 IIartea,*with stellate basal, and branched 

 tentacular spicules), generally compound, 

 increasing by basal budding or by stolons; 

 in the former case, the spicules may be 

 fusiform, or cylindrical, spiny or tuberous, 

 and the polyps retractile (Sympodiumf), 

 or non retractile (Anthelia) ; the outer 

 layer may be smooth and the polyps re- 

 tractile (Lobularia). The stoloniferous 

 forms may have non-retractile, \vart-likc 



s and a creeping, thick coenosarc s P i( ;. lll ;' s of Akyonids 

 ' 

 (Sarcodictvum). The polyps mav be Mun.,^ pranuiosa ; ,/. \i- 



., /T) ,'. . \ cyonium digitatnm; *, J'.i- 



tubular, non-retractile (Rhizoxema), or nlcyoniumelegaii^ 

 retractile, ribbed and spiculigerous (Clavularia), or smooth, 

 non-spiculigerous (Cornularia). 2. Telestidae compound, 

 to a tree- like colony by lateral budding, ex. 

 Telesto. 3. Alcyonidae lobate or branched masses, formed 

 by lateral budding, often granular on the surface. Alcyo- 

 nium is fleshy, lobate, with retractile polyps on all sides; 

 Sarcophytum has a discoidal pedicellated polypieroid, barren 

 beneath ; Ammothea has semi-retractile xooids ; Helonella is 

 capitate, with plaited-mouthed xooids ; Xenia has clustered, 

 non-retractile polypes on the ends of the- branches of a M>U, 

 slightly-brancl. ; Nidalia has a cartilaginous, 



cylindrical stem, with fusiform spicules, the zooids on tin: 

 upper lUTJ .t hemispherical head; Spongndes has a 



uter sur!,. ique, I'IIM- 



form . phtbya has a braiK lied. MIS, granu- 



* '1 i .in imm;itii! 



t 'I 



