90 REPORT OF NATIONAL. MUSEUM, 1923. 



No changes worthy of note have been made in the economic collec- 

 tions. In the hall devoted to Physical and Chemical Geology, a case 

 of " Imitative forms " has been introduced, that is, of specimens the 

 form of which has led to mistaken identifications. As at present 

 arranged, this includes (1) a fossil coral supposed to be a petrified 

 honey comb; (2) a piece of vesicular slag, supposed to be a fossil 

 hornets nest; (3) a chert nodule, mistaken for a fossil egg; (4) a 

 concretion of clay-ironstone thought to be a fossil turtle; (5) an 

 agate, a supposed fossil eye; (6) a rill mark, imitative of a snake; 

 (7) chert nodules and weathered limestones thought to have been 

 fossil human feet; (8) dendritic markings of manganese oxide, sup- 

 posed to be fossil mosses, etc. The imitation is at times quite strik- 

 ing, at other times not, but as an illustration of things which are not 

 what to the casual observer they seem, the exhibit is quite a success. 

 The acquisition of the Coonley-Ward collection, previously men- 

 tioned, made necessary an expansion of the meteorite collection, one 

 case being added. The department is endeavoring to add to the 

 attractiveness and educational value of its exhibits by means of 

 graphic illustrations. The method that has been employed of placing 

 photographs in the cases showing field occurrences of the objects 

 exhibited has not fully accomplished all that could be desired. A 

 series of enlarged photographs, measuring 40 by 60 inches, has been 

 prepared to hang on the walls abo^'e the cases, where they will serve 

 to illustrate the materi«^l exhibited below. The subjects include 

 views of glaciers, glaciated areas, rockweathering, volcanic action 

 and products, erosion, etc. 



Upon Assistant Curator Foshag's return after a year's absence, the 

 examination, classification, and distribution of the accumulated min- 

 eralogical materials was given first attention. The bulk of this was 

 relegated to the study series, but a few of the more notable speci- 

 mens were reserved for exhibition. A critical review of the exhibi- 

 tion hall was then made and a number of changes decided upon. 

 The placing of large specimens released through a rearrangement of 

 the " recent accession " case, resulted in changes in the exhibits of 

 large and miscellaneous specimens. One new case of this type of ma- 

 terial was assembled and installed, and the collection of New Jersey 

 zeolites, the gift of the late Dr. W. S. Disbrow, was modified and 

 rearranged, resulting in a more effective display. Two wall cases 

 at the w^est end of the hall have been utilized to present an exhibit 

 showing crystal forms. One hundred well jeveloped natural crystals 

 are here mounted on the shelves, while the table part of the cases 

 contains an equal number of larger crystals showing physical char- 

 acteristics. Another entirely new exhibit is made up of jade and its 

 substitutes. Two large indi^ddual exhibits, nephrite cut from a 

 large boulder, and descloizite from southwestern Africa, mentioned 

 previously in this report, have been installed upon pedestals. 



