CCELENTERA TES. 



so that the whole structure looks like a spiral staircase constructed of fine cord. 

 The accompanying illustration shows an allied form (Streptocaulus) of the family 



Chrysogorgoviiidce, as yet found only in the Western 

 Atlantic. The simple or branched colonies are as thin 

 as horsehair, and the delicate axis has a golden sheen, 

 with a beautiful display of colours. 



The genus Isis, the stock of which is partly horny 

 and partly purely calcareous, forms a transition between 

 the above and the red coral (CoraUium rubrum). In 

 the latter the axis is calcareous, and built of numerous 

 fine layers, the microscopic structure of which is so 

 definite that a connoisseur can detect false from real 

 coral. The fresh axis is covered with fine longitudinal 

 furrows, in which run the deepest of the canals connect- 

 ing the polyps with one another. The stocks, as a rule, 

 consist either purely of male or purely of female in- 

 dividuals, although occasionally the two sexes are found 

 on one and the same stock, and even individual polyps 

 which are both male and female sometimes occur. In 

 the illustration, a slightly magnified branch of a stock 

 is represented, with several retracted polyps and two 

 cut open. In the upper exposed calyx (o), eggs are seen, 

 while the lower (t) contains a large male vesicle, and at 

 its side an egg (o). After hatching, the ciliated larvae 

 leave the egg while still within the chambered cavity of 

 their parent (B). Two of the long worm-like larvae (/, g) 

 can be seen in the illustration through the delicate body- 

 wall of a polyp whose tentacles are retracted, and others 

 are visible in a cell which has been cut open. In the 

 uppermost cell a larva (a) is seen in the act of passing 

 out through the mouth (b). The red coral is found only in 

 the Mediterranean and Adriatic seas; the most noted coral- 

 fisheries being carried on off the Algerian and Tunisian 

 coasts, at depths of forty to one hundred fathoms. The 

 coral obtained in these fisheries varies greatly in value. 

 The price of the broken pieces, often perforated by worms 

 and sponges, is from five to twenty francs the kilogramme 

 (2 Ibs.); good coral fetches from forty-five to seventy francs, 

 while choice thick coral, especially the rosy red kind, is 

 bought at from four hundred to five hundred francs the 

 kilogramme. Such pieces as are black, either superficially 

 or throughout their whole thickness, are sold separately 

 at from twelve to fifteen francs the kilogramme; these are 

 not of a different species, but, having long been covered with mud, have changed colour 

 as a result of chemical changes. The coral is made into articles of ornament both 

 in Paris and Marseilles, but the chief industries are in Naples, Leghorn, and Genoa. 





CORKSCREW SEA-FAN 



pulcherrimus (nat. size). 



