304 American Geologist. ^^y* ^^^ 
Monilopora amplexa Rowley. 
Figs. II, 12, 13, 14, 15, 16. Showing joints of crinoid columns girt 
about by this peculiar coral. 
Fig. 19. A large, long column with a great swollen zone occasioned 
by two or more girdling corals. 
Figs. 17, 18. Swollen stems produced, no doubt, by parasitic guests 
as apparently indicated by pits and shallow depressions. 
This coral was originally described in the June, 1901, num- 
ber of the American Geologist, under the name of Aulopora 
amplexa. It undoubtedly belongs to professor Grabau's genus, 
Monilopora and is refigured on the accompanying plate to 
show the manner of growth and to account for certain protub- 
erances and enlarged sections of crinoid stems often noticed by 
collectors in the Burlington limestone. 
From most of the accompanying figures, it is evident that 
the coral attached itself to the stem of the living crinoid and 
there lived and grew until it was enveloped by the growing 
stem. 
Like the sting of an insect to the twig of a tree, the girding 
Monilopora on the living crinoid stem gave rise to an excre- 
scence or enlargement of the column. 
In figure 11 we find a healthy young coral encircling a 
small, round stem joint that never grew after the attachment 
of the coral or, less probable, the stem was dead when the 
coral began its growth. 
In Figure 12 the coral was, perhaps, dead before the crin- 
oid stem ceased to grow, so also in figures 13 and 14, as evi- 
denced by the broken Monilopora cups, and stem as well, in 
figure 15. 
In figure 13 the after growth of the crinoid stem has en- 
tirely surrounded the girding stem of the coral and has almost 
done so in figure 14. the cup ends of the coral appearing as 
entrances to tunnels. 
In figure 15 the Monilopora has been destroyed after the 
separation of the crinoid stem from its head and has left a 
circular passage around the stem, broken into in places. 
In figure 16 the crinoid column and coral have grown to- 
gether and perhaps died together as the Monilopora cups are 
entire despite the fact the crinoid column has enveloped the 
coral stem. 
