No. 464.] STAGES IN LAGENIDE 549 

the individual again resume a costate condition by the merging 
together of the tubercles. 
Spines. — In the preceding species, C. echinata d'Orb. (Fig. 
18), the loss of spines is a very evident character in senescence. 

Fic. (srcholl, b ta d'Orh h 3 1 $ 


h 

Fıc. = C. carcass ing f spi 
FIG. 20 leata d'Orb., showing similar loss of spines (After Brady.) 

In the median portion of growth the peripheral spines at the 
sutures are long, at least equalling the length of the chamber 
on the peripheral margin. The third from the last is shorter 
and the last two spines decrease progressively in size, the last 
one being very short, while at the last suture no spine at all is 
developed. Much the same condition of affairs in regard to the 
reduction and loss of spines is seen in C. calcar Linn. (Fig. 19), 
in which, however, the spines do not coincide with the suture 
lines. Another excellent example, although not in the same 
family, is that presented by Bulimina aculeata d'Orb. (Fig. 20). 
Here the early growth is marked by well developed spines. As 
growth progresses, the spines of successively added chambers 
are not so greatly developed. Toward the later growth, traces 
of them are seen in the very reduced spines at the posterior 
angles and on the last-formed chambers they are lacking, and 
the chambers are perfectly smooth. 
These examples of loss of ornamentation as a character in 
senescence are exactly comparable to cases already worked out 
