174 RKCENT MADREPOBARIA OF THE HAWAIIAN ISLANDS AND LAYSAN. 



Willi in a ciilice. These spines join radially the trabecuhv of the same septum. Very 

 cli'licate tabulii' rather almiulant. 



The cohnnella is lax, formed by the irregular fusion of the inner septal ends. A 

 small terminal tubercle usually present. 



Zoca/if I/. -Uiiwa'iiiUi Islands, Wilkes Exploring P^xpedition. 



JieMarJLS.^-This coral has a very striking facies, but it is extremely difficult to 

 give an adequate description. The characters seem to lie in the coarse, rough texture 

 and the general irregularity of most of the skeletal elements. The preceding more 

 or less unsatisfactory description, taken in connection with the figures, will it is hoped 

 render the species determinable. 



2. PORITES COMPRESSA Dana. 

 Plate LXVII; Plate LXVIII, fig. 3 (from Dana's type). 



1846. Pontes mordax var. elongaia Dana, Zooph. Wilkes Expl. Exped., p. 553, pi. Liii, fig. 4. 

 1846. Porites compressa Dana, Zooph. Wilkes Exp\. Exped., p. 553, pi. lui, figs. 5, 5a. 

 1852. Porites compressa Milne Edwards and Haime, Ann. Sd. Nat., 3ieme ser., Zool., XVI, p. 31. 

 1860. Porites cumpresm Milne Edwards, Hist. Nat. Corall., Ill, 176. 



1886. Porites biilhosa Cii-ELcii, Reef Corals, Chall. Rept., p. 180, pi. xi, figs. 7, 7a. 

 1836. Porites compressa Qcelch, Reef Corals, Chall. Kept., p. 180. 



1887. Porites compressa Rathbun, Proc. I'. S. Nat. Mus., X, p. 361. 



1905. Porites hawaieiisis secunda Bernard, Porites of the Indo-Pacific, p. 100. 

 1905. Porites hawaiensis (juinta Bernard, Porites of the Indo-Padtic, p. 101, pi. ix, fig. 8. 

 1905. Porites hawaiensis septima Bernard, Porites of the Indo-Pacific, p. 104, pi. x, fig. 1; pi. 

 XII, fig. 6. 



Original description,. — According to Dana this species was as follows: 



Cespitose, alive for U to 2 inches, sublauiellate and erect, coalescing below, lobed above or 



lobato-raniose, lobes compressed, one-half to three-fourths of an inch broad (rarely U inches), short 



(one-half an inch), subtruncateat summit, and to 3 to 4 lines thick, not at all clavate. Corallum firm; 



cells one-half a line broad, neatly polygonal, (|iiite shallow, piano-conical; septa acute and very thin. 



******** 



The clumps are 6 inches or more broad and 4 high, but are alive only at summit for 2 inches or 

 less. Below it is very coalescent, almost forming a solid mass, with a few large vacuities. In some 

 specimens the broad lamellate structure is scarcely apparent. The depth of the conical cells scarcely 

 exceeds one-fourth the breadth, and the septa are very thin. 



The following description is based on Dana's tj'pe, Cat. No. 711, U.S.N.M. 



The corallum is composed of ascending, truncate, compressed, plate-like branches, 

 that t)V fusion form wide, irregular plates. The base is broken, but it can be seen 

 that branching begins (>arly, the branches largel}' fusing one to another in the lower 

 portion of the corallum. Height, 10.3.5 cm.; length, 14.4 cm.; breadth, 8.35 cm. 



Calices polygonal, 1-1.75 mm. in diameter, with about 1.4 mm. as an average, 

 moderately deep, as much as 0.6 mm. The walls near the upper ends of the branches 

 are simple, rather tall, thin, and often zigzag; near the lower limit of the living 

 portioiLS they arc not so tall, or even may be obscured; they are composed of vertical 

 trabecuhe, joined together by thin synapticula, which may be rather wide in a verti- 

 cal plane; perforations may be scarce, l)ut usually are abundant. The upper mural 

 edge is somewhat irregularly but not coarsely dentate; denticles may correspond to 

 the outer ends of the septa; some of them may fork and present a delicately spinulose 

 appearance. 



