^VLCYONAIHAN CORALS. . 9 



These analyses are remarkably concordant and show that the stony corals contain little 

 besides calcium carbonate. Silica and sesquioxides are probably extraneous; magnesia is alto- 

 gether subordinate, although fairly regular in its amount; phosphates occur only in traces. The 

 older analyses all tell the same story, except that in six analyses by S. P. Sharpies ' of corals 

 from the Gulf Stream from 0.27 to 0.84 per cent of calfiiim phosphate was determined. In 

 hve analyses of Brazilian corals, L. R. Lenox * found from 0.42 to 0.54 per cent of magnesium 

 carbonate, quantities like those appearing in our tables. In short, the uniformity of the data is 

 so marked that it is unnecessary to reproduce all the published analyses here." 



ALCYONARIAN CORALS. 



The alcyonarians, which include the red corals, the gorgonias, or sea fans, and other similar, 

 generally branching forms, differ from the madrepores in being notably magnesian. To this 

 rule one exception is Icnown, the genus Heliopora, which stands quite alone and resembles the 

 ordinary corals not only in structure but also in chemical composition.'" With this exception, 

 the alcyonaria are chemically similar to the crinoids, but some genera are much richer in phos- 

 phates. In some respects the alcyonarians arc difficult to deal with analytically, for many of 

 them have a horny axis, composed chiefly of organic matter, surrounded by a cortex or envelope 

 which is largely calcareous. These two portions of the structure are so unlike in composition 

 that imperfections in a sample taken for analysis may lead to very uncertain conclusions. 



The list of alcyonarians analyzed is as follows: 



1. Helioporn cernkaVaMai^: blue coral. Southern Philippine Islumls. The blue color comIsIs of organic matter." 



2. Tubipora purpurea LamarcK. Singapore, Straits Settlements; latitude, 1° 20' N.: longitude, 103° 50' E. 



3. CoralUwn elatior Tiidley: a red coral. Murotsu, To.sa (Shikokui, J.apan; latitude, about 33° N. 



4. Primnoa reseda Verrill. East of Nova Scotia; depth of water, 366 meters; latitude, 42° 16' N.; longitude, 63° 15' \V. 



5. Lepidisis caryophyllia Verrill. Off Nantucket Shoals, Albatross station 2037; latitude, 38° 53' 00" N.; longitude, 

 69° 23' 30" W.; depth, 3,168 meters; bottom temperatiu-e, 3.3° C. 



6. Pennatula acrdeala Dana. St. Peters Bank and Banquereau; Albatross station 2470; latit\ide, 44° 47' N., 

 longitude, 56° 33' 45" W.; depth, 410 meters; bottom temperature, 4.5° C. 



7. Paramurieea borealis Verrill. Southwest edge of the Grand Banks; depth, 641 to 732 meters. 



8. Paragorgia arborea Milne-Edwards and Haime. La Have Ridge, off Nova Scotia. 



9. Alcyonium carneinn L. Agassiz. Albatross station 2468, off Newfoundland; latitude, 45° 11' 30" N.; longitude, 

 55° 51' 30" W. ; depth, 70.9 meters; bottom temperature, 0.5 °C. This analysis, of very pure material, replaces the 

 unsatisfactory one given in the former edition of this paper. Analyst, R. M. Kamm. 



10. Gorgonia sujf'rutieosa Dana. Fiji Islands. Cortex and axis together. 



11. Gorgonia acerosa Pallas. East end of Long Cay, Nassau, Bahamas; latitude, 25° 5' 6" N. C'ortex and axis. 



12. Gorgonia acerosa. Caesars Creek, southern Florida; latitude, 23° 30' N., approximately. Cortex alone. 



13. Muricea humilis Milne-Edwards. Parahyba do Norte, Brazil; latitude, 7° to 8° S. 



14. Muricea cchinata Valenciennes. Cape San Lucas, Lower California; latitude, 22° 52' N. 



15. Plexaurella grandiflora Verrill. Mar Grande, Bahia, Brazil. 



16. Ctenocella pectinnta Valenciennes. Torres Straits, Australia; latitude, about 10° S. 



17. Xiphogorgia anceps Pallas. Caesars Creek, southern Florida; latitude, 23° 30' N., approximately. 



18. Rhipidogorgia Jtabellum hinne. Bermuda; latitude, about 32° N. 



19. Rhipidogorgia Jiabelluin. East side of Andros I.sland, Bahamas; latitude, about 25° N. 



20. Leptogorgki pulchra Verrill. La Paz, Ciulf of Clalifornia; latitude, 24° 26' N. 



21. Leptogorgia rigida Verrill. Cape San Lucas, Lower California; latitude, 22° 52' N. 



22. PhyllogoTgia quereifolia Dana. Fernando de Noronha, Brazil; latitude, 3° 50' S.; longitude, 32° 25' W. 



' .Sharpies, S. P,, Am. ,Toiit, Sci., 3d ser., vnl. 1, p. 168, 1S71. 



* Lonox, L. R,, Harvard roll. Mus, Comp, Zool. Biill., vol. -(4, p, 204, 1901, In a iiieraoir by J, C. Branner on sandstone reefs. 



» See also .SUliman, B., jr.. Am. ,loiir. Sci,, 2d sor,, vol. 1, p, 1S9, IS4f'i, for 31 analyses of corals from the South Pacific and the Indian Ocean; 

 Forchhamraer, C, Neues Jahrb,, 1S.52, p. S54, on magnesia in shells and corals; Nichols, H. W,, Field Columbian Mus. Pub. HI. p, 31, 1906; also, 

 for determinations of magnesia. In C(flnria dxdalea from Abyssinia Nichols found 0..35 per cent of MgCOg. A. G. Uogbom, (Neues Jahrb., 1894, 

 Band 1, p. 262) in two Bermuda corals found 0.36 and 0.62 per cent of MgCOj. 



'0 See Moseley, U . W., Philos. Trans., vol, 166, p. 91, 1876, on the structural relations of Ildiopora. 



" See Moseley, U. W., op. cit., and Bourne, G. C, Philos, Trans,, vol, 1S6, p. 15.5, 189,'>, 



