REPORT OF NATIONAL MUSEUM, 1913. 31 



successive bays each about 18^ feet across, furnishing appropriate 

 dimensions for these several exhibits. As little material had been 

 prepared for them before the occupation of the building, they will 

 remain in a formative stage for some time yet, though in several 

 subjects the installations are sufficiently advanced to be opened to 

 the public. These are as follows: The eggs and nests of birds, animal 

 architecture, phases of evolution, mimicry, albinism, melanism, the 

 cotton boll weevil, and the distribution of the Rocky Mountain 

 grasshopper. Another special exhibition already fully installed 

 consists of the beautiful collection of corals secured by the United 

 States Exploring Expedition around the World from 1838 to 1842, 

 under command of Lieut, (afterwards Rear Admiral) Charles Wilkes, 

 U. S. Navy, comprising a large share of the type specimens described 

 by James D. Dana in his classic work on the subject. 



GEOLOGY. 



The exhibition collections of the department of geology are classi- 

 fied and arranged under four general heads, namely, systematic 

 geology, mineralogy, applied geology and paleontology. 



Systematic geology. — Systematic or physical and chemical geology 

 occupies the eastern section of the east range in the first story to a 

 distance of 131 feet 4 inches from the adjoining wing, with a floor 

 area of approximately 6,769 square feet. First in order come the 

 rock or petrological exhibits, installed m 1 wall and 5 upright floor 

 cases. They begin with a series of the more common elements found 

 in either a free or combined state in the rocks forming any essential 

 feature of the earth's crust; are followed by a series of the ordmary 

 rock-forming minerals representing the combinations of these ele- 

 ments, and these, in turn, by a series illustrating all the common 

 rock types in the form of hand specimens about 3^ by 4h inches in 

 lateral dimensions. Supplementing these mtroductory collections 

 are several series showing the changes which rock masses have under- 

 gone through chemical and dynamic agencies, such as crushing, 

 faulting, and the various phases of metamoi-phism. They are con- 

 tained in 7 upright floor cases of double-unit size, and are classified 

 as follows: Rock weathering, glacial jihenomena, concretions, faults 

 and other structural forms, calcareous and siliceous sinter, cave 

 phenomena and other iUustrations of cold water deposition, vol- 

 canoes and volcanic phenomena, deep-sea dredgings and minor 

 geological phenomena. 



Constituting an especially interestuig featm-e of the hall are the 

 meteorites, which, while properly classed as rocks, are kept apart as 

 illustrating world-making materials. The collection fills 1 large and 

 2 smaU cases, and an especially large example is mounted on a separate 

 base. It numbers 713 specimens, repres editing 321 falls, and ranks 

 32377°— NAT Mus 1913 3 



