20 J. D. Dana on Zoophytes. 
74. As an Echinopora is related to the Astrea argus, so the 
foliaceous Meruline are related to the Meandrine and those As- 
treeas that increase by disk buds. They are foliaceous Meandri- 
ne excepting a few species which are branching. The Monti- 
cularic differ from the Meandrine only in this; that the ridges 
of the latter are reduced in the former to isolated prominences, by 
a cross coalescence of the disk lines. The disk, instead of being 
prolonged, in a single line, is widened in two or three, and thus, 
this effect is produced. We have then a gradual passage from 
the Monticularia with a compound reticulate disk to the Astrea 
with a simple circular disk, and the differences depend upon the 
prolating disk subdividing or not, or its prolating in more lines 
than one. ‘There are some branching Merulinas so closely ap- 
proaching the Monticulariz, that it is difficult to decide upon 
the genus to which they should be referred. 
75. If the disk should widen in every direction, instead of in 
particular lines, still another variety would result not yet men- 
tioned. The F'ungide are instances of this. The simple spe- 
cies (Fungiz) are polyps without margins to the disks ; and the 
compound species (e. g. Polyphyllize, Herpetolithi, Pavoniz, As- 
trea siderea of Lamarck, &c.) have no intervals between the 
stars or disks. Like the lamelle at the bottom of a trench in a 
Meandrina, the lamellae of the stars pass wninterruptedly from 
one centre (oririme) to another, and this is their characteristic. 
Yet there are species with concave cells, because the intervals 
between two polyp-mouths may be prominent, and not because 
the disks are not confluent. 
If the facts here stated appear to 
throw some difficulty in the way of seeerey, 
distinguishing the genera and species “//Rsifii» 
of zoaphytes by their coralla, we may 
say that no fault can be attributed to 
the author, for if any where, it per- 
tains to the zoophytes themselves. In 
this matter we take them as our teach- 
ers. A proper study of recent zo- 
ophytes, we feel assured, will set 
aside to a great extent the apparent 
difficulties. In another place the va- 
rious characteristics will be further. 
dwelt upon. 
76. Modes of Branching.—The 
annexed figure (of a Caulastreea ) illus- 
trates. a common mode of branching 
the ramose species. It is a re- 
the mode of disk budding al- 
ready ibed (¢ 47.) On one 
branch two polyp-mouths already ex- 
sult of 
