402 POLYPI. 



MADREPORA, Lamarck, 



Or his Madrepores proper, the whole surface is roughened by little stars 

 with projecting edges. 



In his POCILLOPORA we observe little impressed stars with pores in the 

 intervals. 



In his SERIALOPOHA, these little stars are disposed in linear ranges. 



A- HO i. Lamarck. 



A broad surface, usually convex and excavated by crowded stars, each 

 containing a polypus furnished with numerous arms, but on a single range, 

 in the centre of which is the mouth. 



When it is a plane surface, or forms broad lamins covered with stars on 

 one side, it becomes an EXPLANARIA. 



The PORITES are a sort of ramous Astreae. 



When this surface is marked with elongated lines, like little valleys sepa- 

 rated by transversely furrowed hills, we have the MEANDRINA, Lam. 



In each valley, and from space to space, we find mouths, and the tentacula, 

 instead of forming rosettes round them, form a range along the sides of the 

 valley. In some species they are totally wanting, the margin of each mouth 

 being merely festooned. 



If the hills which separate these valleys are raised in leaves or crests, sul- 

 cated on both sides, it is a PAVONIA. Mouths, usually without tentacula, are 

 found at the bottom of the valleys. 



When these hills are conical, or like projecting stars, we have the HYDNO- 

 FHORA of Fischer, and the MONTICULARIA of Lamarck. They should be 

 distinguished according to the situation of their Polypi, which are at the sum- 

 mit of the projecting parts, as in Oculina, or at the bottom of the cavities, as 

 in Meandrina. 



ACARICINA. 



The Agaricinse are composed of laminae hollowed on one side only by the 

 valleys, which are themselves sulcated. 



It is thought that we may approximate to the Madrepores in general, certain 

 corals (Polypiers) or the SARCINULA, Lam., composed of cylinders, a section 

 of which forms stars, by reason of the projecting laminae which traverse the 

 interior. When there is a solid axis in the middle of these lamina? we have 

 SxvUiNA. These corals are perhaps as nearly related to the Tubiporae. 



MILEPORA, Linrueus, 



Where the stony portion is extremely various in form, and the surface merely 

 marked with little holes or pores, or even without any apparent orifices. 

 In the third tribe, or the 



NATANTES, 

 The axis is stony but not fixed. 



PENNATULA, Linnceus. 



A common body, free from all adhesion, of a regular and constant form, 

 and susceptible of locomotion by the contractions of its fleshy portion and the 



