Introduction to Animal Morphology. 1 1 1 



tons, which may be (a) isolated, or amalgamated with a horny* 

 or chalky interstitial substance (axis of Melithaea, &c.), 

 or (/?) lamellated, with or without an organic basis (as 

 Gorgonia or Primnoa), or (y) crystalline, increasing by 

 chalky deposits, with scarcely an organic basis (Madrepores). 

 Spicules (Sclerodermites) are fusiform, laminar, ovoid, or 

 stellate ; a spicular skeleton is *. potypitnid ; one continuously 

 calcified, a poh'parium or coraUum ;f the hard tissue is 

 renchyma, which may be compact or porous. Each 

 -ona (Corallite) of a polyparium consists of some of the 

 following parts : i. A calcified, ab-oral foot, continued in 

 colonial forms into the ccenenchyma. 2. The calcified 

 vnderon of the persona (theca) forming the wall of the cup 

 V.v) ; this may consist of two layers, an endo- and an exo- 

 theca. 3. Calcified mesenteries (septa'l), passing in from the 

 vndotheca, dividing the calyx longitudinally into radially- 

 arranged loculi. 4. Rib-like ridges on the outside of the 

 rxotheca, opposite each system or between two (costaf). 

 :<le the exotheca, an ecderonic investing layer or 

 <pitheca may form, often developed in inverse ratio to the 

 thickness of the theca. 6. Between the simple zooids of a 



* Apparently horny, but really chitinoid ; intermediate between Chitin 

 and Keratin. 



t Analysis of Coral gives 89-96 per cent, of Calcium Carbonate; 

 0-3-250 of Calcium and Magnesium Phosphate and Fluoride ; 0-50 organic 



with traces of Silica, Iron, Alumina. Magnesium Moride is present 

 There is, however, much variety. Silica may in some 

 - ; -T cent. ; Magnesia, 45 per cent. The specific gravity of 

 111 2-2O 2-8o. 



: primary folds form the first, the 



;.ve or six). Between tlu-M- a third c\vle 



interval. The fourth < ts of 



id third, and one of still 



:id and third. The filth . 



in the lilt : \\-cen tin 



: ami fifth ; an eighth 

 !rr after the tlin 



ill follow 

 -.her thus : i, 0, 4, 3, 8, 5, 7, 2, 7, 5, 8, 3, 4, 6, i, &c. 



