BULLETIN 59, UNITED STATES NATION.U. MUSEUM. 173 



I. PORITES MORDAX Dana. 



Plato l.XVl; Plate LX.KIII, figs. 3, 3a. 



1846. Porites mordax T>At;.\., Zoopli. Wilkes Expl. Exped., p. 552, pi. i.iii, figs, 3, 3a. 



1887. Porites viordax Rathbun, Proc. U. S. Xat. Mus., X, p. 364. 



1905. Porites hawaiensis prima Bernard, Porites of the Indo-Pacific, p. 99. 



OHijinal description. — Daiia'.s original description is as follows: 



Cespitose, alive for 3J to 4 inches; branches subsimple and somewhat c()inpres.*ed telow, often 

 coalescing into a plate, branchlets 1 J to 2 incliea long, one-third of an inch thick, and one-third to 1 

 inch broad, piano-rotund at apex. Corallum strong and firm, with the surface harsh; cells large 

 (three-fourths of a line), deep, and conical; septum acute, scabrous. 



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Forms rather open clumps, 10 inches broad and 6 to 8 high, consisting of stout branches, often 

 united below into thick plates or cavernous masses. The texture is firm and the surface peculiarly 

 rough and harsh, being pitted with large deep cells, having septa, often with the angles prominent 

 There are seven or eight cells in a brea<lth of half an inch. Some specimens are massive and sub- 

 lamellar, with obtuse lobes above, instead of proper branches. 



There is one of Dana's original specimens in the United States National Museum, 

 No. 710. It fulfills well the requirements of his description and corresponds with 

 his figure, but apparently- is not the figured specimen. The dimensions of this 

 specimen are: Length, 2-J- cm.; width, 14 cm.; height, V6 cm. The general aspect is 

 as Dana described it. 



The calices are rather large, 1.5 mm. in diameter, except in the angles between 

 l)ranches and on depressed portions, where they usually are much smaller. Tiie 

 walls are distinct, simple, and rather thick; composed of vertical trabecuhe, bound 

 together by synapticula. These synapticula usually are rather .stout bars; the wall 

 therefore looks rather thick and solid when viewed from above; in places they may 

 not extend to the tops of the .septa, then the walls appear interrupted. Sometimes 

 there are synapticula near the wf 11 in the interseptal loculi, but they are irregular, 

 not forming a definite, constant ring as in other species. The edge of the wall and 

 the .septal knots on it are almost glabrous; the absence of the minute spinulations, 

 so coUHUon in many species of Pm'itix^ was so .striking that at tirst it was thought the 

 surface ornamentation was worn away. The corners of the walls between the calices 

 are frequently somewhat elevated. The depth of the calices is moderate. 



Normally there are twelve septa, the dorsal directive, four latei'al pairs, with the 

 inner ends of the ventral triplet free or only loosely fused. The septa are coarse, 

 rather thick, rareh' straight; each has, includ.ing the paliforni tooth, a few coarse, 

 irregular dentations; the fusion of the iinier .septal ends is not according to any detinite 

 scheme. There are no minute granulations, but on the faces are a few large, irregular 

 ones. The pali are extremely ii-regulai' in development, sometimes present, some- 

 times absent; when present they are knots of no detinite shape or size. Outside 

 of the palar ring each septum usually has a single coarse dentation near the wall. 

 Each sPiJtiim pos.sesses between the palus and the wall one trabecula. The traba- 

 cida" are irregidar in size, usually coar.se, and are joined to those of neighboring septa 

 by coarse, irregularly shaped synapticula. The largest synapticula are those in the 

 wall. Occasionally spines projecting subhorizontally inward can be seen near the 



