UNKNOWN ATLANTIC OK WEST INDIAN PORITES. 87 



Before dividing, the stems flatten Uj straight, chisel-like edges, 2 cm. wide and niort;, ami 

 than 1 cm. thick. The living layer extends from 5 to 6 cm. downwanls. The coral dies 

 progressively upwards, without extnision of tabulate or epithecal films. 



The calicles are about 1 mm. across,, deep at the growing tips, and gradually getting flush 

 with the surface at the lower edge of the living layer. The wall-thread is im^'ular, seldom 

 very zigzag, and gets gi-adually coarse and thick ; the wall itself descends steeply into the 

 calicle. The septa are short, thick and truncate, rather than knoblxid. The radial .symmetry Is 

 not easy to make out, except for the six to seven deep open holes representing the intcrseptal 

 loculi. A coarse thread represents the columellar tangle ; it is sometimes a ring which surrounds 

 an open fossa ; from it the pali rise as thick, but slightly tapering rods, sometimes very 

 large, but nearly always very irregular. Five principals can occasionally be made out. 



This is the description of another of the Paris Museum specimens (No. Z 182 k), named 

 Porites davaria. It again shows the typical forking of the West Indian l)ranching forms, 

 with a remarkable specialisation in the sharp, chisel-like edges of the terminals. Once again, 

 here is a method of growth -quite unlike that of the type of Lamarck's davaria, or, indeed, 

 any other I have yet seen. 



74. Porites West Indies x. 9. (1\ Americaiia incertce sedis nana.) (PI. XIV. fig. 2.) 

 [West Indies, colL Michelin ; Paris Museum.] 



Description. — The corallum rises into an expanded tuft, from a ha.sal stem, somewhat 

 thin, but irregularly flattening and swelling. Tliis departure from the usual symmetrically 

 cylindrical stems and the irregularity of the forking, is characteristic of forms with thickening 

 stems and branches (see Table III. E. d, p. 136). The living layer is 2*5 cm. deep. Distinct 

 epithecal rings appear. 



The calicles are 1 mm. in diameter, angular, but never quite superficial. The walls are 

 thin and steep, appearing at the surface as granular tlireads, very often incomplete. The septa 

 are very irregular in length, being frosted gi-anules when projecting from the sides, but longer 

 when projecting from the angles of the calicle walls. The ring of pali is conspicuous, as five 

 frosted granules ; the fossa is here and there open, though mostly with a columellar tubercle. 



The skeleton is open and loose with large interseptal loculi The colour is a very pallid 

 buff. 



This is another of the Paris Museum specimens (No. Z 182; ), which has been placed 

 with Lamarck's davaria. But it obviously belongs to the unkno\vn West Indian forms, 

 inasmuch as the growth shows an interesting variation on a type of branching abready 

 mentioned several times (see e.g. P. Porto Rico 3), only here there is some indication that the 

 swollen tips are chieUy flattened (see remarks under P. Guadalupe 2, p. 43;. 



