INTRODUCTION. XXlll 
3. Genus DuNDRACIS. 
Milne Edw. and J. Haime, Comp. rend., t. xxix, p. 70, 1849. 
Corallum arborescent ; coonenchyma almost compact, with its surface granulated. Cadices 
sub-mammiform. No columella. Septa not exsert, or only very slightly so ; nearly equal. 
Typ. sp., Dendracis Gervillii, nob. ; Madrepora Gervillii, Defrance, Dict. des Sc. Nat., vol. xxviii, p. 8; 
Michelin, Icon., Zooph., pl. xlix, fig. 8. 
4. Genus ARRACIS. 
Milne Edw. and J. Haime, loc. cit., p. 70, 1849. 
Corallum massive; ccenenchyma spongy, with its surface echinulate. Ca/ices with a 
thin projecting margin. No columella. Septa unequally developed, entire. 
Typ. sp. Areacis spheroidalis, nob.; Astrea spheroidalis, Michelin, pl. xliy, fig. 9. 
Family II. 
ASTREID A. 
Dana, Exploring Expedition, Zooph., p. 194, 1846. 
Corallum composite or simple, circumscribed by imperforated walls, and often 
increasing by fissiparity. Corallites becoming tall by the progress of their growth; each 
individual or series of individuals well defined, and separated from the others by perfect 
walls. Ccenenchyma not existing, or being formed either by the development of the coste 
and their dissepiments, or by the epithecal tissue alone, and not forming a compact mass 
as in the Oculinidee. he visceral chamber never obliterated inferiorly by the growth of 
the walls, but subdivided and more or less completely closed up by the imterseptal dis- 
sepiments, which are in general very abundant ; never any synapticule like those of the 
Fungide. 
First Tribe—EUSMILIN As. 
Septa completely developed and entire (that is to say, with their apical margin neither 
lobate nor denticulate). Coste always unarmed. Co/wmella often compact, or even styliform. 
Section I—EUSMILIN A) PROPRL#. 
Corallum simple or composite, and in that case formed by distinct corallites, affecting 
an arborescent disposition, fasciculate, or presenting a linear arrangement ; free laterally, 
at least in a great part of their length, and never having their calices blended together. 
Reproduction usually fissiparous in the compound species. 
