REPORT ON THE ALCYONARIA. 



li 



scales or spiny ueecllcs. The spines or thorns usually project bej'ond the surface of the 

 crenenchynia, and give it a rough or spiny appearance. In the polyps are distinguishable 

 a calycine (not retractile) region, a median oesophageal region, and a tentacular region. 

 The median region can be withdrawn into the calycine portion, so that in the retracted 

 ^^tate the tentacular portion rests directly upon the calycine margin. Around the bases 

 of the tentacles lies a ring of peripherally disposed calcareous spindles, forming the collaret. 

 The tentacles fold together down upon the calyx; their bases are well furnished with 

 spicules. When the polyp is contracted the armoured tentacle-bases form an eight- 

 rayed operculum, closing up the calyx. 



This family is the richest in specific forms of the Holaxonia. These may be grouped 

 into several genera, chiefly diagnosed from the shape of the spicules, besides which 

 there is to be taken into account the more or less different methods by which the tentacles 

 are retracted witliin tlie calyx. This retraction is least developed in Acanthogorgia and 

 Muriceides, which are, as regards their polyps, nearest perhaps to the Ceratoisidinse. 

 The power of retmction increases, however, in the succeeding genera, until in the case of 

 Muricea, complete concealment within the calyx becomes possible. This last genus 

 forms a transition to the Plexauridae. 



In the subjoined list, all the genera which have been fully diagnosed by Verrill in 

 his various memoirs are accepted. Of the numerous genera recorded by Gray, only those' 

 ai'e retained which have been reinvestigated either by Ridley or the authors. Gray's 

 diagnoses being based upon very trivial characters are in most cases insutKcient. 



1. Acanthogorgia, Gray, emend. 



Verrill. 

 2.' Paramuricea, Kolliker, emend. 



Verrill. 



3. Hypnogorgia, Duchassaing and 



JNIichelotti. 



4. Muriceides, Wright and Studer. 



5. Anthomuricea, Wright and Studer. 



6. Clematissa, Wright and Studer. 



7. ViUogorgia, Duchassaing and 



Michelotti, emend. Ridley. 



8. AntJiogorgia, Verrill. 



9. Menella, Gray. 



lU. Placogorgia, Wright and Studer. 



11. Echinomui'icea, Verrill. 



12. Echinogorgia, Kolliker. 



13. MenaceUa, Gray, emend. Ridley. 



14. Heterogorgia, Verrill. 



15. Astrogorgia, Verrill. 



16. Behryce, De Phillipi. 



17. Acamptogorgia, Wright and Studer. 



18. Tliesea, Duchassaing and Michelotti. 



19. Ads, Duchassaing and Michelotti. 



20. Elasmogorgia, Wright and Studer. 



21. Muricella, Verrill. 



22. Eumurlcea, Verrill. 



23. Muricea, Auct., emend. Verrill. 



