NATURE OF CORAL ANIMALS. 69 



good red herring," spiders, par excellence, being with them prominent representatives of 

 this popular omnium-gatherum class. Insects, in the technically accepted interpretation of 

 the term, embrace invertebrate animals which in their normal adult condition possess no 

 more, no less, than six jointed ambulatory limbs, or legs, associated with a distinctly 

 articulated body, and a complex nervous, circulatory, and visceral system. The coral animal 

 owns none of these. It is, individually, a simple polyp, comparable in every essential detail 

 with the ordinary simply-organised sea-anemone familiar to every seaside or aquarium visitor, 

 with the exception that it possesses the property of secreting a dense, calcareous, skeleton out 

 of the lime held abundantly in suspension in probably every sea. On the British coast, even, 

 there are a few known coral-secreting anemones, such as the Devonshire Cup-coral, Caryo- 

 phyllia Smithii, and the scarlet and gold Cup-coral, Balanophyllia regia. In the tropical, coral 

 seas there are corresponding solitary species, such as the Mushroom-coral, genus Fungia, 

 illustrated by Plates XXIV., XXV., and Chromo No. VI., which particular type might be 

 appropriately likened to a coral-forming anemone, resembling our largest British species, 

 known as the " Dahlia anemone," Tcalia crassicornis. This calcareous skelton, the possession 

 of which, it should be mentioned, constitutes the most marked distinction betwixt a coral 

 and a sea-anemone, is secreted entirely by the basal tissues of the polyps. The polyps 

 consequently, as shown in some of the accompanying coloured plates, are able, through 

 abundant ingestion of, and distension with, water, to elevate their tentacular crowns to a 

 considerable height above their associated corals. 



Without entering into a detailed account of the more conspicuous structural variations of 

 corals and their polyps, which furnishes the material for a subsequent chapter, the author 

 may remark that the reef-forming corals owe their solidity and extensive dimensions to 

 the fact that they represent, for the most part, the united, or, more correctly, imperfectly 

 separated, coral skeletons or "coralla" of a great number of closely associated sea-anemone- 

 like polyps. The closely aggregated clusters of our commoner British species, such as the 

 strawberry, Actinia mescnibyanthemum, the daisy, Sagartia bellis, and the opelet anemone, 

 Anthea cerens, as they repose extended in their beauty in some clear rock-pool on, say, the 

 Devonshire, Welsh, or Channel Islands coast, have been a frequent source of admiring wonder. 

 The majority of the clusters have been formed by the repeated subdivision, or technically- 

 termed " fission," of a single primary anemone or polyp. Supposing that these clustered 

 anemones secreted a calcareous coral basis, and, in place of becoming entirely separated 

 from one another, remained united by their basal, skeleton-secreting tissues, we should have 

 in this hypothetical compound organism a precise presentment of the structural organisation 

 of a typical reef-forming coral. This brief introductory explanation will, it is trusted, suffice 

 to inculcate a tolerably correct and intelligible apprehension of the true nature and affinities 

 of the long-suffering, reef-constructing " coral insect." 



