Wall 

 cases 1-6 



104 Guide to the Invertehrata. 



CoBlentera. the skeleton is hard and massive, their remains are abundant in 

 GALLERY the rocks, and form one of the most important groups known to 

 Wesfside. ^^^^' geologist. 



Table- I. Anthozoa (or Actinozoa). 



cases 1 9, Subclass 1 . Alcyonaria, or Octocoralla : the Sea Pens, Red Coral, etc. 



,,2. Zoantharia, or Hexacoralla. 



Order 1. Actiniaria: Sea- Anemones. 



2. Antipatharia : Black Corals. 



3. Madreporaiia: the ordinary Corals. 

 ,, 3. Ctenophora : the Venus Girdle {Cestum), the Globe 



Jelly-fish [Beroe), etc. 



Among the Anthozoa one subclass (the Ctenophora) and one 

 order (the Actiniaria, or Sea-Anemones) may be at once dismissed, 

 as they are all soft- bodied animals, and no specimens of them 

 are contained in the collection. The fossil Anthozoa, therefore, 

 all belong either to the subclass Alcyonaria, or to the orders 

 Antipatharia and Madreporaria of the subclass Zoantharia, 



The Alcyonaria form the subclass including all corals in -which 

 the radiating internal partitions (mesenteries and septa) are eight 

 in number, instead of six, and which have fringed tentacles. This 

 subclass is divided into three orders — 



1. Alcyonacea, fixed forms with no central rod-like skeleton. 



2. Gorgonacea, fixed forms with a central rod-like skeleton. 



3. Pennatulacea, free-swimming Alcyonaria, with a flexible, 

 horny stem. 



The Zoantharia, on the other hand, include the forms in which 

 the partitions are usually either six in number or some multiple 

 of six. 



The actual connection between the soft and the hard parts 

 of many of the Anthozoa is, however, often not very intimate. 

 The skeleton alone is therefore not always sufficient to precisely 

 determine the affinities of the animal which formed it. The 

 classification of the fossil corals is therefore tentative and unsatis- 

 factory, and the collection has been arranged stratigraphically. 



The series begins in Table-case 9, and occupies Cases 1-8 and 

 also Wall-cases 1-6. The oldest British fauna represented in the 

 collection comes from the Ordovician rocks of North Wales and 

 Scotland, whence are derived some species of Favosites and Lyopora. 

 These are generally regarded as Zoantharia, the former being 

 included in the section Perforata, an I the latter in that of the 



