202 RECENT MADKEI'OKAKIA OF THE HAWAIIAN ISLANDS AND LAYSAN. 



types of coiiillimi, which will he (l.-scrihed hiter. Tlip upper surface varies in con- 

 forniation; it may he i)laii<> or iiiiuniniUnte. In suhs.H|ueiit growtli successive layers 

 wltli free or closely apijjied hut distinct edg-e.s arc formed one above another; the 

 f>-r()wtli, however, appears to he continuous in the central portion. If the living edge 

 bends downward, tlie base is i-ounded toward its center, but the successive growth 

 layers are indicated: if I Ih^ living edge is curved upward or is subhorizontal, the V)ase 

 shows concentric rims, or the corallum has collars one above another. The corallum 

 in the later stages of growth may lie a mass with a rounded or flatfish upper surface, 

 a head with deep lobations. a mass with a manuniUatc or humpy upper surface, or 

 the surface may be studded with stunii)y protuberances. 



The calices are polygonal, from 1 to 2 mm. in diameter, average about 1.5, 

 usuallv deep, seiiarated i)y tall, straight walls or by distinct wall ridges, with den- 

 tate upper edges. 



The septa are nariow aliovc; there is one septal trabecula between a palus and 

 the wall, with the scjjtal granule variable in development, usually not specially 

 prominent: when distinct it is detai-hed from the wall. Although the granule may 

 be indistinct. process(>s fi-om the septal and mural tra))ecuhv may cause several den- 

 tations to appear on a septal margin. There is either a complete or an incomplete 

 ring of peripheral synapticula. usually detached from the wall. When the ring is 

 complete the wall fi-e(|uenlly has a trinuirate appearance. Septal faces granulate; 

 interseptal loculi open, but often narrow. 



The pali vary in form, lath-like or rounded; the formula is fre(juentl\- or usually 

 conn)lete; when not complete, of tenest suppressed on one or more members of the 

 triplet, less often on the dorsal directive. The inner ends of the triplet, when with- 

 out pali. still remain separate from one another, that is. they do not meet and fuse in 

 the apex of an angle. A palar ring of synapticula is present, and usually complete 



The columella is rather constantly a narrow axial lamella, sometimes an axial 

 j)apil!a, rarely absent. It is joined by radii to the iimer ends of the septa; the colu- 

 in(!lla tangle, (-omposcd of the axial lamella or papilla and the radii from it, is loose 

 in structure or rather c<)m])act. 



PORITES LOBATA forma CENTRALIS subforma ALPHA, new. 

 Plate LXXXIII, tiist'. 2, 2a; Plate LXXXIV, figs. I, la, 1/,. 



Corallum at lirst thin, explanate. incrusting or free, with a miuumillate or humpy 

 upptn' surface; later some of the mammilla' or humps may grow upward and form 

 a.scending lobes or crests. 



The peripheral ring of synapticula is incomplete: the pali, compres.sed. 



Zocalt'lo'x. — Kiih-.uvd. Oalui, W. T. Brigham; Pukoo, Molokai. W. T. Brigham, 

 J. E. Duerden. 



Cotr/jm.— Cut. Nos. 32'241, 22242, IT.S.N.M. 



PORITES LOBATA forma CENTRALIS subforma BETA, new. 



The edge of the living layer is bent under and creeps over a portion of the base; 

 the upper surface of the corallum is irregularly domed and humpy. 



The peripheral ring of synapticula is usually incomplete; pali, compressed. 



