110 CORALS AND CORAL LSLANDS. 



The corals of colder waters, either outside of the coral-reef 

 seas, or at considerable depths within them, comprise, accord- 

 ingly, the following: — 



1. A very few Fungids. 



2. Some of the Oculinids ; many of the Astrangids and 

 Caryophyllids ; many Stylasterids ; a few Stylophorids. 



3. Many of the Eupsammids. 



4. Some of the Gorgonia and Pennatula tribes, and a few 

 of the Alcyonium tribe. 



5. A few Milleporids of the genus Pliobothrus. 



A large proportion of the cold water species are solitary 

 polyps. 



Through the torrid region, in the central and western Pa- 

 cific, that is, within 15° to 18° of the equator, where the tem- 

 perature of the surface is never below 74°F. for any month of 

 the year, all the prominent genera of reef-forming species are 

 abundantly represented — those of the Astraeacea, Fungacea, 

 Oculinacea, Madreporacea, Alcyonoids, Millepores and Nulli- 

 pores. The Feejee seas afford magnificent examples of these 

 torrid region productions. Astrseas and Maeandrinas grow 

 there in their fullest perfection ; Madrepores add flowering 

 shrubbery of many kinds, besides large vases and spreading 

 folia ; some of these folia over six feet in expanse. Mussa? 

 and related species produce clumps of larger flowers ; Meru- 

 linae, Echinoporaa, Gemmipora3 and Montiporse form groups 

 of gracefully infolded or spreading leaves ; Pavonias, Pocilli- 

 poraa, Seriatoporse and Porites branching tufts of a great vari- 

 ety of forms ; Tubipores and Xenise, beds or masses of the 

 most delicately-tinted pinks ; Sponggodiae, large pendant clus- 

 ters of orange and crimson ; and Fungiae display their broad 

 disks in the spaces among the other kinds. Many of the 

 species may be gathered from the shallow pools about the reefs. 



