SOCIALITY IN THE MADREPORARIA 
249 
PLATE III 
1. A small portion of a colony of Diphyphyllum eruciforme, x 1, show- 
ing multiple calicinal budding and intercolumnar braces. A diffuse 
type of colony. Specimen from the Iowa Silurian; furnished by 
the Geology Department, State University. 
2. Portion of colony of Lithostrotion canadense var. proliferum Hall, 
X 1, top view. Also a diffuse type but with the columns contiguous 
and without intercolumnar braces. Specimen from Iowa Mississip- 
pian; negative furnished by Geology Department, State University. 
3. Portion of colony of Lithostrotion canadense Castelnau, x 1. A more 
compact type which has assumed the polygonal shape of column 
due to crowding. The double nature of the intercolumnar walls 
is not apparent in the picture. Specimen from Iowa Mississippian ; 
negative furnished by Geology Department, State University. 
4. Portion of colony of Acej-vularia inequalis H. & W., x 1. A still more 
compact type, with single intercolumnar walls. Specimen from 
Iowa Devonian; negative furnished by Geology Department, State 
University. 
5. Balanophyllia socialis. An example of solitary Hexacorallum. From 
Bourne (1905). 
6. Caryophyllia, with un detached bud, x !.♦ Specimen from about sixty 
fathoms, off Barbados, British West Indies. 
7. An unidentified specimen from Barbados, showing parent corallite 
and three generations of buds in place. 
8. Dendrophyllia profunda Pourt., x showing formation of a den- 
droid colony by successive lateral buds partly embedded in coenen- 
chyma. Specimen from Florida, 230 to 400^ fathoms. 
PLATE IV 
1. Ampfiihelia, x A more complex dendroid colony formed by 
alternate marginal budding, with dichotomous branching caused by 
twin-budding. The newly-formed calices have the original trumpet 
shape of solitary cup-corals but later become embedded in coenen- 
chyma. 'Specimen from Barbados, 50 to 100 fathoms. 
2. Oculina robusta Pourt., x > 2 . A' further development of the coenen- 
chyma idea. Deposition of coenenchyma keeps pace with the out- 
ward growth of the calices, and this., together with the greatly 
increased diameter and much more numerous calices per unit area, 
makes this one of the most compact of dendroid colonies. Speci- 
men from Florida reefs. 
3. Dendrophyllia diaphana Dana, x 1. The large size, trumpet shape, 
and comparative fewness, of the calices, as well as the small amount 
of coenenchyma, mark this as a primitive type of colony. From 
Vaughan (1918, Plate 60, Fig. 3a). 
4. Dendrophyllia willeyi (Gardiner), x A slightly more advanced 
type than 3. From Vaughan (1918, Plate 60, Fig. 4). 
5. Galaxea fascicularis (Linn.), x A still more advanced type of 
spreading colony. The calices are reduced in size and increased 
