xl BRITISH FOSSIL CORALS. 
60. Genus PLESIASTREA. 
Milne Edw. and J. Haime, Comptes rend., t. xxvii, p. 494, 1848. 
Corallum globose ; its under surface having the form of a naked costulated plate. 
Gemmation extra-calicular. Calices with a free margin, and a fossula rather shallow. 
Columella spongy. Pali well developed, and corresponding to all the septa except those 
of the last cyclum. Sepa exsert, formed by a well-developed lamina, and having a deli- 
cately-serrated apex. Coste and their dissepiments in general well developed. 
Typ. sp., Plesiastrea Urvillit, Mine Edw. and J. Haime, Ann. des Sc. Nat., vol. x, tab. ix, fig. 2°; 
Astrea galavea, Quoy and Gaim., Voyage de l’Astrolabe, Zooph., pl. xvii, figs. 10-14. 
61. Genus LEpTastREA. 
Milne Edw. and J. Haime, Comptes rend., t. xxvii, p. 494, 1848. 
Corallum very dense and incrusting, and increasing by fissiparity, as well as by 
extra-calicular gemmation. Costal ccenenchyma quite compact. Calices in general much 
crowded together, but preserving their margins distinct. Colwmella papillose. Septa thin, 
closely set, exsert, delicately granulated, and having their apical margin almost entire near 
the walls, but delicately denticulated towards the columella. Dissepiments not very abun- 
dant. Coste rather mdistinct. 
Typ. sp., Leptastrea Roissyana, Milne Edw. and J. Haime, Ann. Se. Nat., 3™ serie, vol. x, tab. ix, fig. 6. 
62. Genus SOLENASTREA. 
Milne Edw. and J. Haime, Comptes rend., t. xxvii, p. 494, 1848. 
Corallum forming im general a convex mass, of a light and cellular structure. Gem- 
mation extra-calicular. Corallites long, slender, and united by an exothecal structure, 
and not by the coste, which do not meet, and are often rudimentary.  Calices circular, 
with an exsert margin. Colwmella spongy, and in general small. Septa very thin; their 
margin denticulated. Dissepiments simple, numerous, and closely set. 
Typ. sp., Solenastrea Turonensis, nob. ; Astrea Turonensis, Michelin, Icon., pl. Ixxv, figs. 1, 2. 
63. Genus PHYMASTREA. 
Milne Edw. and J. Haime, Comptes rend., t. xxvii, p. 494, 1848. 
Corallum formmg a convex or a horizontal mass. Corailites prismatical ; surrounded 
from top to bottom by a thin epitheca ; very nearly approximated to each other, but not 
united by their walls, and cemented together by means of a certain number of large 
wart-like processes, so as to leave an empty space between them. Gemmation extra- 
calicular. Calices sub-polygonal, with a free margin. Colwmella spongy, well developed. 
Septa large, shghtly exsert, and strongly dentated. Walls thick ; no trace of coste. 
Typ. sp., Phymastrea Valenciennesii, Milne Edw. and J. Haime, Ann. Se. Nat., 3™ série, vol. x, 
tab. 1x, fig. 3. 
