Orthothetes Minutus, N. Sp. — Cuininiiigs. 147 
If such tetrahedral collapse be granted in the case of the 
earth, then the existing arrangement of oceans and conti- 
nents receives a natural explanation. 
The changes in the distribution of land and seas in the past 
may be explained as due to the conflict of two opposing forces, 
collapse caused by the earth's contraction producing deforma- 
tions, which are reduced by the efifects of the earth's rotation. 
Geological history aflfords evidence of the alternation of per- 
iods of tetrahedral collapse and spheroidal recovery. 
The plan of the earth may, in short, be attributed to the 
continual foundering of the earth's external shell, owing to 
the unceasing shrinkagre of its internal mass. 
ORTHOTHETES MINUTUS, N. SP. FROM THE SA- 
LEM* LIMESTONE OF HARRODSBURG, IND. 
By E. K. Cum MINGS, Bloomington, Iiul. 
I'late XV. 
The specimens described in the present paper are from the 
abandoned quarry known as the Cleveland Stone Company's 
quarry located one mile north of Harrodsburg, Monroe county, 
Indiana. This quarry is in the Salem limestone, and the speci- 
mens come from the top layers of the quarry and also from 
near the summit of the formation. They are associated with 
abundant representatives of the entire Spergen hill fauna, and 
are so far as I can ascertain specifically identical with the 
forms from Spergen hill referred by Hallt to Streptorhyncluis 
( Orthis ) innhraculum Schlotheim. 
DESCRIPTION OF PLATE XV. 
Fig. I. Ventral valve of a specimen 4.75 mm. broad. 
Fig. I a. Dorsal valve of a specimen 5.5 mm. broad by 4 mm. long. 
Fig. 2. Profile view of a specimen 5 mm. long. 
Figs. 3, 4, 5. Ventral, profile and cardinal views of a specimen o.g 
mm. broad and 0.6 mm. long. 
Figs. 6, 7, 8. Three views of a specimen 2 mm. broad which has an 
abnormally convex ventral valve and an abnormally short area. 
Only one such specimen was found and it is possible that it may 
l)rove to belong to a distinct species. 
• Th« name Salem is suggested by the writer in a paper now in press in place 
of the name Bedford as applied to the oolitic limestone of Indiana, the latter 
name having been for many years preoccupied as the name uf the Bedford shale 
of northeastern Ohio. 
t Trans. Alb. Inst., vol. iv, p. 12; Indiana Geol. and Nat. Hist., 12th .\n- 
niial Rcpt., p. 325. 
