'The importance of geographic isolation for tributed species, Scotoplanes globosa and Molpa- species formation has long been recognized for dia blakei, are in the same area replaced by the well-investigated groups of terrestrial animals. cIosely related species, S. clarki and M. granulata. The deep sea, however, with its uniform and A clinal variation is present in the deimatid stable environment and its almost complete ab- Orphnurgus glaber, which ranges from the Bay sence of geographic barriers, seems to offer few of BengaI to the Hawaiian Islands. possibilities of geographic isolation, apart from The deep sea has sometimes been regarded as the discontinuous environment of the hadal a refuge for ancient animal groups which are no zone. longer able to stand the competition at shallow The distribution and geographic variation of depths. This view of a low degree of competition a number of species of holothurians suggest that is hardly compatible with the high faunal diver- geographic isolation with a subsequent subspe- sity recently found in abyssal communities. cies and species formation has taken place in an The existence and dominance of an animal abyssal region along the Pacific coast of Central group in the deep sea depend on its ability to America and northern South America. Two wide- compete successfully in this particular environ- ly distributed species, Deima ualidum and Onei- ment. The Elasipoda is a pronounced example rophanta mutabilis, are in this area represented of a group which owes its dominance to its highly by geographic subspecies. Two other widely dis- evolved adaptation to life in the deep sea. v. REFERENCES Agatep, C. P., 1967a: Elasipod holothurians of Antarctica, Belyaev, 6. M., 1966: Bottom fauna of the ultra-abyssal I. Genus Amperifnu Pawson 1965. - Bull. Sth. Calif. depths of the World Ocean. - Moskva. 248 pp. (In Rus- Acad. Sci. 66: 54-68. sian. English translation 1972: Hadal bottom fauna of - 1967b: Some elasipodid holothurians of Antarctic and the World Ocean. Jerusalem). Subantarctic seas.-Antarctic Res. Ser. 11: 49-71. - 1970: Ultra-abyssal holothurians of the genus Myrio- - 1967c: Holothurians of the genera Elpidia and Kolga trochus (order Apoda, £am. Myriotrochidae). - In: V. 6. from the Canadian Basin of the Arctic Ocean. -Bull. Bogorov (Ed.): Fauna of the Kurile-Kamchatka Trench Sth. Calif. Acad. Sci. 66: 135-141. and its environment. Trudy Inst. Okeanol. P. P. Shir- Alton, M. S., 1966: Bathymetric distribution of sea stars shova 86: 458-488. (In Russian. English translation 1972: (Asteroidea) off the northern Oregon coast.- J. Fish. I-fadal holothurians of the genus Myriotrochus. Jerusa- Res. Bd Can. 23: 1673-1714. lem. - Proc. Shirshov Inst. Oceanol. 86: 482-515). - 1971: Deep water holothurians of the genus E1pidia.- Andersen, hI., 1971: Echinodermata from J@rgen Brenlund In: V. G. Bogorov (Ed.): Fauna of the Kurile-Kamchatka Fjord, North Greenland. - Meddr Grenland 184, 12: Trench and its environment. Trudy Inst. Okeanol. 1-18. P. P. Shirshova 92: 326-367. (In Russian). Anikouchine, W. A. & Hsin-Yi Ling, 1967: Evidence for - & M. E. Vinogradov, 1969: A new pelagic holothurian turbidite accumulation in trenches in the Indo-Pacific (Elasipoda, Psychropotidae) Oom the abyssal of the region. - Mar. GeoI. 5: 141-154. Kurilo-Kamchatka Trench. - Zool. Zh. 48: 709-716. (In Arrhenius, G., 1963: Pelagic sediments. -In: M. N. Hill Russian, English summary). (Ed.): The sea 3: 655-727. - & N. G. Vinogradova, 1961: Investigations of the bottom Augustin, E., 1908: Ueber japanische Seewalzen. - Abh. fauna in the Java Trench. - Okeanologiya 1: 125-132. bayer. Akad. Wiss. Math.-phys. K1. Suppl. 2, 1: 1-45. (In Russian). Bailey, W. B., 1956: On the origin of the deep Baffin Bay Birshtein, Ya. A., 1957: Certain peculiarities of the ultra- water. - J. Fish. Res. Bd Can. 13: 303-308. abyssal fauna at the example of the genus Storthyngura Baranota, Z. I., 1957: Echinoderms of the Bering Sea.- (Crustacea Isopoda Asellota). - Zool. Zh. 36: 961-985. (In Issled. dal'nevost. Morei SSSR 4: 149-266. (In Russian). Russian, English summary). - 1964: Echinoderms collected by the "F. Litke" expedition Boolootian, R. A,, A. C. Giese, J. S. Tucker & A. Farman- in 1955. - Trudy arkt. antarkt. nauchno-issled. Inst. 259: farmaiau, 1959: A contribution to the biology of a deep 355-372. (In Russian). sea echinoid, Allocentrotus fragilis (Jackson). - Biol. Barham, E. G., N. J. Ayer, Jr. & R. E. Boyce, 1967: Macro- Bull. mar. biol. Lab., Woods Hole 116: 362-372. benthos of the San Diego Trough: photographic census Bruun, A. F., 1956: The abyssal fauna: Its ecology, distri- and observations from bathyscaphe, "Triestem.-Deep bution and origin. - Nature, Lond. 177: 1105-1108. Sea Res. 14: 773-784. - 1957: Deep sea and abyssal depths. - In: J. W. Hedg- Barnard, J. L., 1961: Gammaridean Amphipoda from peth (Ed.): Treatise on marine ecology and paleoeco- depths of 400 to 6000 m. - Galathea Rep. 5: 23-128. logy 1: Ecology. - Mem. geol. Soc. Am. 67, 1: 441-672. Brunn, A. F., 1958: General introduction to the reports Deichmann, E., 1930: The holothurians of the western and list of deep-sea stations. - Galathea Rep. 1: 7-48. part of the Atlantic Ocean. -Bull. Mus. comp. Zool. - k T. Wolff, 1961: Abyssal benthic organisms: Nacure, Harv. 71: 41-226. origin, distiibution, and influence on sedimentation. - - 1936: Notes on Pennatulacea and Holothurioidea col- In: M. Sears (Ed.): Oceanography. Invited lectures lected by the First and Second Bingham Oceanographic presented at the International Oceanographic Congress Expeditions 1925-1926. - Bull. Bingham oceanogr. ColI. held in New York, 1959. - Publs Am. Ass. Advmt Sci. 5, 3: 1-11. 67: 391-397. - 1940: Report on the holothurians, collected by the Har- Buchanan, J. B., 1963: The bottom fauna communities and vard-Havana Expeditions 1938 and 1939, with a revision their sediment relationships off the coast of North- of the Molpadonia of the Atlantic Ocean. - Mems Soc. umberland. - Oikos 14: 154-175. cub. Hist. nat. "Felipe Poey" 14: 183-240. Carter, G. S., 1961: Evolution in the deep seas. - In: M. - 1954: The holothurians of the Gulf of Mexico.- Sears (Ed.): Oceanography. Invited lectures presented Fishery Bull. Fish Wildl. Serv. U. S. 55: 381-410. at the International Oceanographic Congress held in Diiben, M. W. von k J. Koren, 1844a: Om Holothurier- New Uork, 1959. -Publs Am. Ass. Advmt Sci. 67: 229- nas Hudskelett. - I<. svenska VetenskAkad. Handl. 1844: 237. 211-228. Caullery, M., 1925: Sur la structure et le fonctionnement - - 184415: Ofversigt af Skandinaviens Echinodermer. - des gonades chez les bchinides. - Trav. Stn 2001. Wime- Ibid.: 229-328. reux 9: 21-35. D'yakonov, A. IM.,1949: Keys to the echinoderms of the - & M. Siedlecki, 1903: Sur la rksorption phagocytaire des far-eastern seas. - Izv. tikhookean. nauchno-issled. Inst. produits gknitaux inutilisks chez 1'Echinocardium cor- ryb. Khoz. Okeanogr. 30: 1-132. (In Russian). datum Penn.- C. r. hebd. Skanc. Acad. Sci., Paris 137: - 1952a: Echinoderms from abyssal depths near Kam- 496-498. chatka. - Issled. dal'nevost. Morei SSSR 3: 116-130. Cherbonnier, G., 1952: Contribution a la connaissance des (In Russian). Holothuries de 1'Afrique du Sud.- Trans. R. Soc. S. - 1952b: Echinodermata of the Chukotsk Sea and Bering Afr. 33: 469-509. Strait. - In: Fauna and Flora of the Chukotsk Sea. - 1964: Myriotrochus bruuni Hansen, Holothurie apode Akad. Nauk SSSR: 286-310. (In Russian). rkcoltke, en 1962, par le bathyscaphe "Archim&de", dans - Z. I. Baranova k T. S. Savel'eva, 1958: Notes on the la Fosse du Japon. Volume jubilaire dkdik B Georges Holothurioidea of the South Sakhalin and South Kurile Petit. -Vie Milieu, Suppl. 17: 169-172. Islands area. - Issled. dal'nevost. Morei SSSR 5: 358-380. Clark, W. L., 1907: The apodous holothurians. A mono- (In Russian). graph of the Synaptidae and Molpadiidae. - Smithson. Edwards, C. L., 1907: The holothurians of the north Pa- Contr. Knowl. 35: 1-231. cific coast of North America. - Proc. U. S. natn. Mus. - 1913: Echinoderms from Lower California. -Bull. Am. 33: 49-68. Mus. nat. Hist. 32: 185-236. Ek~nan,S., 1925: Holothurien. - Further zool. Results - 1920: Holothurioidea. Rep. scient. Results Exped. Tro- Swed. Antarct. Exped. 1, 6: 1-194. pical Pacific [and] Eastern Tropical Pacific. 'Alba- - 1926: Systematisch-phylogenetische Studien uber Elasi- tross". - Mem. Mus. comp. 2001. Harv. 39: 115-154. poden und Aspidochiroten. - Zool. Jb. (Anat.) 47: - 19'3a: Echinoderms from Lower California (Supple- 429-540. mentary Report). - Bull. Am. Mus. nat. Hist. 48: 147- - 1927: Holothurien der deutschen Sudpolar-Expedition 163. 1901-1903 aus der Ostantarktis und von den Kerguelen. - 1923b: The echinoderm fauna of South Africa. - Ann. - Dt. Siidpo1.-Exped. 19 (Zool. 11): 359-419. S. Afr. Mus. 13: 221-435. - 1947: Uber die Festigkeit der marinen Sedimente als Clarke, A. H., Jr., 1962: On the composition, zoogeography, Faktor der Tierverbreitung. - Zool. Bidr. Upps. 25: origin and age of the deep-sea mollusk fauna. -Deep 1-20. Sea Res. 9: 291-306. -. 1953: Zoogeography of the sea. - London. 417 pp. k Cognetti, G. R. Delavault, 1962: La sexualit6 des astkri- Fairbridge, R. W., 1966: Trenches and related deep sea des. - Cah. Biol. mar. 3: 157-182. troughs. - In: R. W. Fairbridge (Ed.): The encyclopedia Coull, B. C., 1972: Species diversity and faunal affinities of oceanography. New York: 929-939. of meiobenthic Copepoda in the deep sea. - Mar. Biol. Fell, H. B., 1967: Biological applications of sea-floor pho- 14: 48-51. tography. -In: J. 3. Hersey (Ed.): Deep-sea photography. r_,k,=$-, L. ec c. ~~;;.~d~ff,1948: v-1-~i~~urall~i~ciurnt ---"---- des Johns Hopkins oceanogr. Stud. 3: 207-221. kchinodermes. - In: P. P. Grassk (Ed.): Trait6 de zoolo- gie 11: 3-363. Fisher, W. K., 1907: The holothurians of the Hawaiian Islands. - Proc. U. S. natn.