THE ANTHOZOA 61 



formed by retrograde formation into short tubes' or stomidia. Genera 

 Polystomidium, Hertwig ; Polysiphonia, Hertwig. FAMILY 5. AMPHIAN- 

 THIDAE. Malacactineae embracing by their bases stems of Gorgonidae ; 

 with shortened sagittal and elongated transverse axis, circular muscle 

 mesogloeal. Primary septa alone complete, but sterile. Genera 

 Stephanactis, Hertwig ; Amphianthus, Hertwig ; Gephyra, von Koch. 

 (Possibly the genus Savaglia with twenty-four tentacles and twenty-four 

 mesenteries must be placed here. It was formerly classed among the 

 Antipatheae.) FAMILY 6. DENDRACTIDAE. Some or all of the tentacles 

 ramified or foliaceous. SUB-FAMILY RHODACTINAE. Genera Rhodactis, 

 M. Edw. ; Taractea, Andres. SUB-FAMILY PHYMANTHINAE. Genera 

 Phymanthus, M. Edw. ; Triactis, Klunz. SUB-FAMILY PHYLLACTINAE. 

 Genus Phyllactis, M. Edw. SUB-FAMILY CRAMBACTINAE. Genus 

 Grambadis, Haeckel. SUB-FAMILY CRYPTODENDRINAE. Genus Crypto- 

 dendron, Klunz. FAMILY 7. THALASSIANTHIDAE. The disc is covered 

 with peculiar appendages, which are not tentacles, and are termed fronds. 

 Each frond is villose, pinnate, or tubercular. SUB-FAMILY THALASSIAN- 

 THINAE. Genera Thalassianthus, Leuck ; Actineria, Blainv. ; Megalactis, 

 Ehrb.; Actinodendron,~Ehr}). SUB-FAMILY SARCOPHIANTHINAE. Genus 

 Sarcophianthus, Lesson. 



GROUP B. 



Malacactineae in which precocious development of the secondary and 

 succeeding cycles of mesenteries obscures the hexameral arrangement 



FAMILY 1. TEALIIDAE. Genus Tealia, Gosse. FAMILY 2. POLYO- 

 PIDAE. Genus Polyopis, Hertwig. FAMILY 3. SICYONIDAE. Genus 

 Sicyonis, Hertwig. 



For the characters of these three families, see p. 46. 



The classification of the Malacactineae given above must be 

 considered provisional. As far as possible the lines laid down by 

 Hertwig (41) have been followed, as his classification is based on 

 anatomical characters. But the anatomy of many forms is still 

 undescribed, and .where anatomical characters are wanting the 

 arrangement of Andres (1) has been followed. 



SUB-ORDER 2. SCLERACTINIAE ( = MADREPORARIA). Actinideae 

 provided with a calcareous skeleton secreted by cells called calico- 

 blasts, which actually are or represent the basal ectoderm. 



The anatomy of the soft parts of any Scleractinian resembles, 

 in essential points, that of an Actinia. There are complete and 

 incomplete mesenteries arranged in cycles, the sequence of numbers 

 being usually 12, 12, 24, 48, etc., as in Hexactiniae. Usually two 

 couples of directive mesenteries are present, but in a few forms 

 (Mussa, Lophohelia, and Euphyllia) there are no directives. For 

 a detailed account of the anatomy of such corals as have been 

 studied, the reader is referred to the works of von Koch (51, 57, 



