102 ZOOPHYTES. 
temperate zone, and are common upon some portions of our own 
coast. 
Order Actinoidea. 
101. The Actinoidea are marine zoophytes. All oceans have their 
species, yet in the torrid zone they more especially abound, and display 
most variedly their colours and singular forms. 
The soft Actinide and the Alcyonaria have the widest range, 
occurring both among the coral reefs of the equatorial regions, and, 
to the north and south, beyond the temperate zone. The Mediter- 
ranean affords species of Gorgonia, Corallium, and Alcyonium, besides 
numerous Actiniew. The coasts of Britain have also their Aleyonia 
and Actinias, and from far in the northern seas, come the Umbellularia, 
and some other species of the Pennatula family. 
Among the coral-making Actinaria, the Madrepore and Astrea 
tribes are almost exclusively confined to the coral-reef seas,—a region 
included between the parallels of 28° north and south of the equator, 
—while the Caryophyllia family are spread as widely as the species 
of Actinia. Several species of Caryophyllide occur in the Mediter- 
ranean, and others in the high northern seas, and they are met with 
at depths of several hundred feet. ‘They are also common among 
the coral-reefs of the tropics. 
The Madreporacea and Astraacea, with the Gemmiporide, are the 
principal constituents of coral reefs. The temperature limiting their 
geographical range is about 68° F., this being the winter temperature 
of the ocean on the outskirts of the reef-growing seas. ‘The waters 
sometimes sink to 66° or even 64°, but this appears to be a temperature 
which they can endure, and not that in which they germinate. ‘The 
extremes which they will survive prove only their powers of endurance, 
and do not affect the above statement; for their geographical distribu- 
tion will be determined by the temperature which limits their powers 
of germination. 
The temperature in the warmest parts of the Pacific varies from 80° 
to 85°, and here Astraas, Meandrinas, Madrepores, &c., are developed 
with peculiar luxuriance, along with thousands of other strange and 
beautiful forms of tropic life. From the above temperature to 72°, 
does not appear to be too great a range for the most fastidious species. 
At the Sandwich Islands, which are near the northern limits of the 
coral seas, Porites and Pocillopore prevail, and there are very few 
species of the genera Astrea, Mussa, and Meandrina, which are com- 
mon nearer the equator. 
