TRIBE I. ASTR^ACEA. 335 



flat surface, without valleys or cells. They approach also the Psam- 

 mocorse, but these have the lamellae more or less indistinct and rag- 

 gedly though minutely denticulate, giving the surface a sanded ap- 

 pearance. 



The genus Agaricia of Lamarck included only the unifacial species 

 of these two subgenera, together with some other unifacial corals, of 

 the genus Manopora Blainville's Montipora and the A. ampliata. 

 For the last, as already stated, Ehrenberg instituted the genus 

 Merulina. 



Arrangement of the Species. 



SUBGENUS 1. UNDAHIA. Unifacial, superior surface transversely rugate, with minute 

 oririmes at the bottom of the furrows (rarely others on the ridges) : no distinct cells 

 in any part. (The species are arranged in the order of the prominence of the ridges, 

 which, in the planulata, are obsolescent, with some nearly superficial cells.) 



*1. A. undata. *4. A. levicollis. 



*2. A. rugosa. *5. A. planulata. 



*3. A. speciosa. 



SUBGENUS 2. MYCEDIA. Unifacial or bifacial ; surface either transversely rugate with 

 at least the marginal rugae consisting of a series of cells, or else every where reticulate 

 with fossa; made up of cells. Texture firm, lamellae minute and neatly regular. 



I. Unifacial. 



*6. A. Myced. cucullata. *8. A. Myced. fragilis. 



7. A. Myced. purpurea. 



II. Glomerate from an explanate base. 

 *9. A. Myced. gibbosa. 



III. Foliaceous, bifacial. , 



*10. A. Myced. agaricites. *11. A. Myced. cristata. 



SUBGENUS I UNDARIA. 



AgaridcE transverse rugatce ; superfaie nusquam cellis nullis exca- 

 vatd ; oririmis minutis fossarum fundo dispositis. 



Transversely colliculate ; no excavate cells in any part ; oririmes 

 minute and arranged along the bottom of the fossa?. 



