250 



SCIENCE 



[N. S. Vol. XLIII. No. 1103 



In conformance with a plan for zoological ex- 

 ploration designed eventually to cover all of South 

 America, the American Museum of Natural His- 

 tory began, in 1910, field work in Colombia. Since 

 that time, eight expeditions have been sent to that 

 country and thousands of specimens of birds and 

 mammals and pertinent information in regard to 

 the country they inhabit have been secured. The 

 identification of this material having now been 

 nearly completed data are for the first time avail- 

 able to determine the life-zones of the Colombian 

 Andes and the faunal areas of each zone. Four 

 zones can be defined with surprising definiteness: 

 A tropical, extending from sea-level to approxi- 

 mately 5,000 feet; a subtropical, extending from 

 5,000 to 9,000 feet; a temperate, extending from 

 9,000 to 12,500, or the upper limit of tree-growth, 

 and an alpine or Paramo zone, extending from 

 the timber line to the lower limit of snow, or ap- 

 proximately 15,000 feet. 



Having determined these zones on the basis of 

 collections and field studies, the investigator is 

 now prepared to consider the problem of their 

 faunal areas and of the origin of the forms occu- 

 pying the zones above the basal or tropical zone. 

 A detailed report on these and allied questions, 

 together with an outline of the distribution in 

 Colombia of each of the over 1,300 species and 

 subspecies of birds secured is now approaching 

 completion. 



General Aspects of Zoological Exploration in 

 South America: Wilfeed H. Osgood. 

 Zoological exploration with particular reference 

 to the higher vertebrates has to-day a greater sig- 

 nificance than even a very few years ago. Aside 

 from the increased importance it has owing to its 

 reciprocal relations with advances in other sciences 

 than zoology, it differs from earlier work in that 

 it follows a definite plan and applies itself con- 

 sistently to a particular region. Moreover, meth- 

 ods of preserving specimens and keeping records 

 are such that the subsequent study of the mate- 

 rial has infinitely greater possibilities than for- 

 merly. It is evident also that results rapidly be- 

 come cumulative, for as collections grow larger 

 and more comprehensive the problems on which 

 they may be brought to bear become broader and 

 more far reaching. 



Until recently, knowledge of the fauna of .South 

 America has depended upon scattered data gath- 

 ered sporadically and variously isolated in difiEer- 

 ent parts of the world. Detailed systematic study 

 and explorations continued over a period of years 



opens up a host of problems not only in classifica- 

 tion and distribution, but also in phylogeny, ecol- 

 ogy, evolution and relations to human affairs. 

 Especially in the study of mammals there is a wide 

 field promising important results. No general 

 work in the mammals of South America has even 

 been attempted and there is scarcely a single genus 

 of which the geographic distribution is known in 

 detail. Ignorant of the facts of distribution, we 

 are of course still far from a knowledge of their 

 causes. Among problems of great interest are 

 those dealing with the derivation of the fauna 

 and recent work is throwing considerable light 

 upon the relations of living and extinct types. 

 From the economic standpoint, faunistic work in 

 South America may prove to be of even greater 

 importance than it has been in northern countries, 

 as for example in the control of disease and in the 

 advance delimitation of regions naturally suited 

 for agricultural development. 



The Corals and Coral Beefs of the Gulf of Mex- 

 ico and the Cariibean Sea: Thomas Wayland 

 Vaughan. 



After calling attention to the three bathymetrie 

 zones represented by the corals in coral reef areas, 

 the factors which determine the locus of corals of 

 different grovrth f acies in the shoal waters of such 

 areas were indicated. The discussion of the fac- 

 tors determining the lower bathymetrie limit of 

 shoal water corals included an account of the rela- 

 tive capacity of corals to remove sediment from 

 their surfaces, their mechanisms for catching food, 

 the nature of their food and their relations to 

 light and to temperature. The relations to salin- 

 ity and atmospheric exposure were considered. 

 Experiments on rearing corals, on the determina- 

 tion of the length of the free-swimming larval 

 stage and on the growth rate of corals were de- 

 scribed. 



The relations of off-shore reefs to the submarine 

 platforms around the Gulf of Mexico and the 

 Caribbean Sea, viz.. Mosquito Bank, Compeche 

 Bank and the Floridian Plateau, and to the sub- 

 merged terraces of the Virgin Islands, the Saint 

 Martin Plateau and Antigua, were briefiy dis- 

 cussed. It was shown that in Recent geologic 

 time the margins of the Gulf of Mexico and the 

 Caribbean Sea have been submerged by the sea 

 overflowing the marginal land areas, which in 

 Pleistocene time stood higher with reference to 

 the sea-level than at present. Of the living off- 

 shore reefs those of the continents have grown up 

 on recently submerged or more deeply submerged 



