530 



SCIENCE 



[N. S. Vol. LII. No. 1353 



bottom eshibit in colored glass at the Amer- 

 ican Museum of IsTatural History will un- 

 doubtedly call the attention of a considerable 

 circle to the wonderful habits and esthetic 

 forms of these tiny animals. That the mono- 

 graph by Canu and Bassler is a splendid con- 

 tribution to paleozoology goes withoiit saying 

 — the names of the authors are a guarantee 

 of that — what I wish to emphasize is the 

 utilitarian value of such studies. 



The Bryozoa belong to a geologically very 

 old phylum, the vast majority secrete a cal- 

 careous skeleton, and since they are so plenti- 

 ful and so tiny they are preserved as fossils 

 in great abundance at very many geological 

 horizons. They are thus admirably adapted 

 to become medals of creation, and highly 

 satisfactory time markers for geologists. 

 They well illustrate the old aphorism of the 

 importance of the insignificant, since while 

 infinitely varied in detail, their specific limits 

 are usually sharp and their range in time is 

 not too great to enable them to be used with 

 great precision in the determination of the 

 age of geological formations and their corre- 

 lation over wide areas. Their value has long 

 been recognized in the older geological forma- 

 tions of the Paleozoic and Mesozoic, but in 

 this country at least, their usefulness in de- 

 limiting the later formations, has hitherto 

 remained unevaluated. 



Geologic correlation may seem remote from 

 the affairs of the workaday world and yet 

 upon its successful consummation rests not 

 only the understanding of the local and gen- 

 eral relations underground that are the basis 

 of all exploitation of artesian waters, oil, and 

 other mineral resources of the earth, but it is 

 of prime importance in determining the places 

 or origin and the paths of migration of the 

 life of bygone days. The early Tertiary 

 bryozoa of the Atlantic Coastal Plain not 

 only serve to substantiate the evidence derived 

 from other classes of fossils, but may be ex- 

 pected to eventually help determine whether 

 the past floodings of this region were simul- 

 taneous with similar events in the Old World 

 and hence caused by changes in sea level or 

 whether these were due to regional changes 



in the attitude and elevation or depression of 

 the land. 



l^ational Museum Bulletin 103 contains 

 elevent different papers upon the geology and 

 paleontology of the Canal Zone and much 

 additional information with regard to the 

 Antilles, especially with respect to the corals. 

 In fact, if the Mollusca could have been in- 

 cluded, it would serve as a complete manual 

 of the geology and paleontology of that region. 



A Ivnowledge of calcareous algse, either 

 recent or fossil, is confined to a few special- 

 ists. Their fossil remains have never been 

 much used in stratigraphic geology, because, 

 like the bryozoa, diatoms and foraminifera, 

 sufficient intelligence had not been focused 

 upon them to determine their value as indi- 

 cators of horizons, past events, or past phys- 

 ical conditions. It is only recently that their 

 importance in the formation of magnesium 

 carbonate and the great part they take in the 

 formation of the so-called coral reefs of both 

 the past and the present, has been understood. 



The Foraminifera constitute a group of 

 organisms that are exceedingly abundant in 

 existing seas, and useful in a variety of ways 

 in studies of plankton and experimental evo- 

 lution. They belong to the great and prim- 

 itive group of the Protozoa, or unicellular 

 animals, and since, unlike so many of their 

 congeners, they early acquired a siliceous or 

 calcereous skeleton they have been preserved 

 in ever increasing abundance in certain 

 marine formations from the Silurian down to 

 the present. 



Although they have been utilized to some 

 extent abroad, particularly in the recognition 

 of zones in the nummuHtic limestones of the 

 Mediterranean regions, they have attracted 

 but few students in this country, and have 

 been rather generally regarded as lacking 

 in chronologic value. This reputation was 

 largely the result of the specific limits as 

 conceived by English students such as Parker, 

 Jones and Brady, who published large stand- 

 ard works in which single species showed most 

 astonishing ranges of millions of years. Nat- 

 urally forms that live on unchanged for eons 



