276 
trating the simplest form (fig. 16), then the 
upper surface of a similar example with 
central nodes developed (fig. 17), next, two 
such structures joined by a symmetrical 
keystonelike arch (fig. 18), and finally three 
united in a row (fig. 19). 
PLATE 4 
A series of dumbbell concretions with 
modifications, about %4 natural size. The 
simple, bulletlike form (fig. 1) either joins 
with a similar one or develops a new growth 
connected by a band (figs. 2-6). Sometimes 
the end nodes become curiously modified 
(figs. 7, 8), or the middle band may become 
overdeveloped (figs. 9, 10). In figure 11 a 
small typical form is almost engulfed by a 
secondary smooth clay deposit. Further 
modifications are shown in figures 12, 14, 
and 15, while in figure 13 the primary form 
here composed of dark clay has been largely 
-overed by a broad deposit of lighter-colored 
4ay. 
PLATE 5 
A series of botryoidal or grapelike forms, 
all about % natural size, in which the simplest 
concretion is roughly rounded with concen- 
tric growth lines (fig. 1), becomes joined to 
similar associated forms by narrow strands 
(figs. 2, 3), which are absorbed with increased 
growth. Additional nodes are added at 
various angles (figs. 4-7), until a series of 
strange, animal imitative forms develops (figs. 
8-18). ‘The reader can possibly imagine a 
Bactrian camel, sea serpent, hen, ant eater, 
dog, and dinosaur among this assemblage. 
PLATE 6 
Insignia imitations (all natural size except 
figs. 6, 8, 13-18, which are X %%) illustrating 
the regularity of lobe development on top 
. side (figs. 1-17) with bottoms faintly marked, 
an insect imitation (fig. 18), and top and 
bottom views of a tadpolelike concretion 
(figs. 19-21, Schoharie, N.Y.). (Fig. 21, X 2.) 
PLATE 7 
Photographs, about % natural size, of 
various simulating concretionary specimens. 
Capsulelike, etc. (figs. 1-4), turban-shaped 
(figs. 5-9), side and bottom views of the same 
turban-shaped form (figs. 10, 11), globular 
bodies with minute nodes (figs. 12-17), top 
and bottom views of a specimen with parallel 
lobes (figs. 18, 19), globular forms with small 
surface nodes (figs. 20-23), and enlarged view 
showing increase by confluence of nodes 
(fig. 24). 
PLATE 8 
Various types of concretion growth (about 
X % unlesss otherwise stated). Watch-shaped 
ANNUAL REPORT SMITHSONIAN INSTITUTION, 1948 
forms (figs. 1, 2), with terminal node (figs. 
3-5), and a series (figs. 6-10) showing devel- 
opment of upper surface ornamentation, 
four grooved, twisted, and bent forms (fig. 
11, longest specimen 14 inches), a simple 
type (fig. 12) of a dark concretion upon 
which lighter-colored layers have been 
arranged horseshoelike, a flat, elongate, 
dark example with deposit of light-colored 
layer (fig. 13), an elongate twisted form (fig. 
14), and a flat specimen with scalloped edges 
overlain by smooth growth (fig. 15), con- 
voluted globules joined in increasing com- 
plexity (figs. 16-20), and a dumbbell form 
partly covered by large, smooth, lateral lobes 
(fig. 21). 
PLATE 9 
Imitative forms of claystones, all X 4% except 
figure 13, which is X 4%. ‘Trilobitelike speci- 
mens simulating a perfect head and a dis- 
torted one (figs. 1-2), 3-lobed examples (figs. 
3-8), symmetrically lobed forms (figs. 9-12), 
a centrally perforated ring like a door knocker 
(fig. 13, from Rutland, Vt.), various types 
arranged around a central node (figs. 14-21), 
and specimens with flat base (figs. 23, 24), 
showing growth of lobes on medallionlike 
upper surface (figs. 22, 25). 
PLatTe 10 
Unusual forms of clay concretions, all 4% 
natural size. Top and bottom sides of two 
specimens, with corresponding sides identical 
in each (figs. 1, 2); tops of four diverse imita- 
tive forms (figs. 3-6); edge views of elongate, 
twisted forms, the first showing an unusual 
profile (figs. 7-9); an example with confluent 
surface lobes (fig. 10); thin, shell-like imita- 
tion, top and bottom views (figs. 11, 12). 
PLATE 11 
Photographs of sand and clay concretions, 
¥ natural size. ‘Two concretions composed 
of sand and rock fragments cemented by cal- 
cite (figs. 1, 2); top and bottom of a trinodate 
specimen symmetrical on the upper side, 
formed in clay and distorted on the lower 
side which rested in an underlying sand layer 
(figs. 3, 4); top and bottom of a thin, angular 
form (figs. 5, 6) showing attempt at sym- 
metry on upper face (fig. 5); thin types of 
symmetrically lobated forms (figs. 7-9); three 
thin, flat imitative forms (figs. 10-12). 
PLATE 12 
A portion of the Ryegate, Vt., varved-clay 
concretion exhibit in the National Museum 
hall of physical geology. This does not in- 
clude any of the type specimens illustrated 
on plates 1 to 11. 
