GEOGRAPHICAL DISTRIBUTION OF CORALS. 85 



4. In the Madrepora tribe (Madreporacea), all of the 

 Madreporids and Poritids ; many of the Dendrophyllia family 

 or Eupsammids. 



5. Among Alcyonoids, numerous species of the Alcyonium 

 and Gorgonia tribes, and some of the Pennatulacea. 



6. Among Hydroids, the Millepores and Heliopores. 



7. Among Alg?e, many Nullipores and Corallines. 



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 

 C'aryophyllids ; 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 Pacific, 

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

 ture 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 Astr^acea, Fungacea, 

 Oculinacea, Madreporacea, Alcyonoids, Millepores and Nulli- 

 ])ores. The Feejee seas afford magnificent examples of these 

 torrid region productions. Astraeas 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, Echinoponx, Gemmiporse and Montiporae form groups 

 of gracefully infolded or spreading leaves ; Pavonise, Pocilli- 

 porae, Seriatoporae and Pontes, branching tufts of a great 

 variety of forms ; Tubipores and Xeniae, beds or masses of the 

 most delicately-tinted pinks; Sponggodiae, large pendant 

 clusters of orange and crimson ; and Fungiae display their 



