128 LOWER PENINSULA. 



PHILLirSASTR^A, D'Orbigny. 



Synon., Smitiiia, Milne-Edwards. 



Compound astrceiform polyparia, with confluent calyces, destitute 

 of intervening walls, but enveloped at the base of the colony by a 

 common epithecal crust. Calyces horizontally expanded in their 

 margins, excavated by an abrupt central pit, which is usually sur- 

 rounded by an elevated monticulose rim. Radial lamellae linear, 

 carinated on the sides, and crenulated at the edges by the ends of 

 the same carinations. Cycle of the lamellae composed of alternately 

 longer and shorter ones ; the longer lamellae unite in the centre, 

 and form a pseudo-columellar, nodular protuberance, but do not 

 connect into a continuous vertical axis. The shorter lamellae ter- 

 minate on the monticulose rim surrounding the central crateriform 

 cell pit. Interlamellar interstices filled with transverse vesiculose 

 plates, arranged in the peripheral area in arched rows crossing 

 diagonally the direction of the lateral carinae. The transverse septa 

 of the centre are so much intersected by the centrally converging 

 vertical lamellae that the contrast in the structure of the outer area 

 from that of the inner is very much weakened ; the inclosed vesi- 

 culose interstitial cell spaces of the centre are somewhat coarser 

 than the peripheral ones, but it is seldom that larger plates, com- 

 parable with continuous diaphragms, can be noticed. By the 

 greater conspicuousness of these transverse plates in the centre, the 

 genus Pachyphyllum is distinguished from Phillipsastr2ea ; there are, 

 however, so many gradations of transition between the two modi- 

 fications of the otherwise perfectly identical types, that I consider 

 their separation artificial and inappropriate. 



. PHILLIPSASTR.^A VERNEUILLI, Milne-Edwards. 



Size of corallites very different in various specimens. Distance 

 from centre to centre of cell pits from one to one and a half centi- 

 meter. Diameter of the central pits varying from three to five 

 millimeters. Number of lamellae in the circumference of a cell from 



