XII. CRUSTACEA AND LOWER INVERTEBRATA. 101 



2. The Oculinidce, which are usually hard branched corals, with 



but few septa developed in cups of the corallum. Oculina 

 diffisa and Amphihelia infundibulifera are representatives 

 of this family. (See Cases 9 and 10.) 



3. The AstrceidcE, or Star Corals, which are usually of large 



size, and form either rounded masses as in the brain coral, 

 or tufted clusters of simple stems. The septa are mostly 

 produced into sharp denticulata or cutting edges. Astrcea 

 denticulaia, Eusmilia knorri, Galaxea esperi, Coelora 

 lahyrinthiformis are examples of this family. (See Case 9.) 



4. The Fungiidce, or Mushroom Corals.— These usually consist 



of large flat single cups with many strongly developed 



septa. The following are representatives of this family 



Fungia danai, F. repanda, and F. j^cttella. (See Cases 9 

 and 10.) 



Section (B) Perforata.— This section includes only one 

 family — 



The Madreporidce. — Most of the members of this family are 

 large branching species with small cups, and the septa 

 little developed. Madrepora ecMnata, Dendrophyllia 

 nigrescens, and D. ramea are examples. (See Case 10). 



Class v.— ALCYONARIA.— This order includes the fol- 

 lowing families : Alcyonidm, or soft corals ; Pennoiulidoe, or sea- 

 pens ; Gorgoniidce ; and Tuhiporidce. They possess eight plumed 

 tentacles, and the same number of vertical lamellae, or mesenteries. 



1. The Alcyonidse are usually called soft corals, on account 

 of the absence of a continuous hard skeleton : they form lobed or 

 finger-like clusters studded with polyps, having a kind of leathery 

 consistence and the epidermis usually charged with calcareous 

 spicules. Examples are Spongodes florida, Neplitliya chahrolii 

 and Alcyoniuin sp. from Port Jackson, Alcyonium pahnatum, 

 from Naples, preserved with the polyps extended. (See Case 17.) 



2. The Pennatulidae or Sea-pens, are feather-like polyps, 

 having a horny or calcareous axis ; the polyps are confined to the 

 upper part of the stem, and are arranged on leaf-like pinnules, 

 either irregularly around a cylindrical head on one side of a 



H 



