FLORIDA RKEFS. 61 
AsTR.BAXS: tentacles not ilefniitcly liiiiitcil in miniln'r, i1iiiu,l;1i usually not exceeiling one Imnilred, and 
generally much below this number; transvei-se lloors. ilreandrinas, generally referred to Astrteans, 
are higlier than the true Astrtcans, on account of their compound Polyps. 
Flsgid.e: indefinite multiplication of tentacles ; imperfect transverse beams. 
AcTISi.E : indefinite niultiplicalion of tentacles ; soft bodies and no transverse beams. 
If now we compare this structural gradation among Polyps with their 
geological succession, we shall find that they correspond exactly. The fol- 
lowang table gives the geological order in which they have been introduced 
upon the surface of the earth: — 
GEOLOGICAL SUCCESSION. 
Present, Halcyonoids. 
Pliocene, ^ 
Miocene, > Madrepores. 
Eocene, ) 
Cretaceous, 
Jurassic, 
Triassic, 
Permian, J 
Carboniferous, 
Porites 
and 
Astrseans. 
Devonian, > Fungidae. 
Silurian, 
V 
With regard to the geological position of the Actinias we can say nothing, 
because, if their soft, gelatinous bodies have left any impressions in the 
rocks, none such have ever been found ; but their absence is no proof that 
they did not exist, since it is exceedingly improbable that animals destitute 
of any hard parts could be preserved 
