544 THE AMERICAN NATURALIST. |. [Vor. XXXIX. 
In uncoiling as is shown in Fig. 2, there is a decided change in 
the angle of curvature from an acute angle gradually to an 
obtuse one. This seems to be the rule in the stages by which a 
straight growth is produced from a coiled one as is shown again 
in Figs. 11 and 12. In C. schlenbachi Reuss (Fig. 11), the 
uncoiled character is early taken on until on an average only the 
first six to eight chambers are coiled, while the succeeding cham- 
bers which constitute the major part of the whole growth, are 
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Fics 9-12.— Four species of Cristellaria, showing different degrees in the acceleration of the 
character of uncoiling. Blackened chambers show the extent of th escent uncoiled 
Fig. 9, Cristellaria articulata R ady; Fig. 11 
C. schlenbachi Reuss; Fig. 12, C. tezzuis B 
ortion. 
portion uss; Fi 
euss; Fig. ro, y; 
ornemann. (Figures adapted from Brady.) 
uncoiled. Thus the senescent character of uncoiling in this last 
species is more accelerated in its development than in C. s¢ddal- 
ana as it originates much earlier in the onto 
of the individual. 
(Fig. 12) 
chambers, 
geny or life history 
In such a species as C. tenuis Bornemann 
the coiled portion is usually limited to the first four 
| while the last fifteen or more are uncoiled. Other 
specimens of this species show fewer chambers than that fig- 
ured. This speeies is then, even more accelerated in develop- 
ment, for the senescent Character is so accelerated that it 
includes four fifths of the entire number of chambers. In the 
complete return to the strai | 
Sht Nodosarian growth, as shown in 
the last few ch 
ambers of this Species, there is a return to a right 
