Apeil 17, 1896.] 



SCIENCE. 



bll 



for the general public and the student, and 

 consequently should be divided into strati- 

 graphic and synoptic collections. The investi- 

 gator may advantageously make use of 

 both of these series, but will have additional 

 aid in the study collections and the card 

 catalogues. 



In recent years there has been a decided 

 tendency to group all fossils according to 

 their biological rank. This is proper if the 

 chief object of a museum is to teach psdeo- 

 botany and paleozoology. In large mu- 

 seums, however, it is necessary to teach 

 not only everything pertaining to mor- 

 phology, but the sequence of faunas, or his- 

 torical geology, as well. Plants and animals 

 do not occur in nature grouped according 

 to their biological rank, but are associated 

 because of their environment and geological 

 history. If the great bulk of fossils is ar- 

 ranged biologically then the grouping and 

 interactions of the individuals of a province 

 or zone are apt to be lost sight of. Pale- 

 ontologists seeking for the relationship 

 which the various provinces bear to another, 

 or the presence or absence of barriers 

 against the dispersal of floras and faunas, 

 will be seriously embarrassed by any arrange- 

 ment other than stratigraphic. The dual 

 evolution of the horse, or of the Terebratel- 

 lidse among the Brachiopoda, are problems 

 both of the faunal geologist and of the 

 systematic zoologist as well. 



A stratigraphic exhibition collection aims 

 to show only the essential animals and 

 plants of various well-marked geological 

 horizons, and these systematically arranged, 

 both geologically and biologically. It 

 should be sufiiciently extensive to illustrate 

 clearly Historical Geology, or the order of 

 distribution of fossil remains throughout 

 geologic time. 



It is seemingly neither proper nor ad- 

 visable to note all the minor geological 

 horizons in large stratigraphic collections 

 like those of the National Museum. For a 



clear demonstration of the facts of faunal 

 geology, it is sufficient to group all the 

 organisms of the Cambrian system into 

 three divisions, representing the Lower, 

 Middle and Upper Cambrian, respectively. 

 Tke Ordovician system, in like manner, 

 should be separated into Calciferous-Chazy, 

 Trenton and Cincinnati groups. The labels 

 accompanying the species should indicate 

 the minor, or local, geological horizon. 

 Practice has also shown the advantage of 

 grouping together all the fossils of each 

 basin or geological province, since in this 

 way only is it possible to indicate clearly 

 the relations which the various provinces 

 bear to one another. Such an arrangement 

 will necessarily cause duplication of certain 

 species, but this is not objectionable, as the 

 forms recurring in two or more provinces 

 illustrate to what extent geographic dis- 

 persion has taken place. This method of 

 installation was introduced in the Cre- 

 taceous collection of the U. S. National 

 Museum some years ago, by Dr. C. A. 

 White, and has proven practically useful to 

 working paleontologists. It is also in 

 harmony with Sir Henry Howorth's idea 

 that " there should be no attempt made to 

 fill up gaps in one area by inserting evi- 

 dence from another." * 



A stratigraphic collection will also show 

 the introduction in time of the vaiious types 

 of organic beings, and the gradual rise from 

 the ancient and less complex floras and 

 faunas to those of greater complexity char- 

 acteristic of the more recent geological 

 epochs. 



In large museums it is advisable to have 

 distinct and separate paleobotanical, inver- 

 tebrate and vertebrate collections. Fossil 

 plants and vertebrates are often so large 

 and bulky as to require a method of instal- 

 lation quite different from invertebrate fos- 

 sils. In small or local museums the various 

 animals of a zone should be kept together, 



* (Ibidem, p. 323.) 



