UNKNOWN ATLANTIC OR WEST INDIAN PORITES. 87 



Before tiividiug, the stems flatten to straight, chisel-like edges, 2 cui. wide and more, aud less 

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

 progressively upwards, without extrusion of tabulate or epithecal films. 



Tlie calicles are about 1 mm. across, deep at the growing tips, and gi-adually getting flush 

 with the surface at the lower edge of the living layer. The wall-thread is irregular, seldom 

 very zigzag, and gets gradually coarse and thick ; the wall itself descends steeply into the 

 calicle. The septa are short, tliick and truncate, rather than knobbed. The radial symmetry is 

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

 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 jje made out. 



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

 Porites clavaria. It again shows the typical forking of the West Indian branching 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 clavaria, or, indeed, 

 any other I have yet seen. 



74. Porites West Indies ,'■. 9. (7'. Americana inccrtm scdis nona.) (PI. XIV. fig. 2.) 

 [West Indies, coll. Michelin ; Paris Museum.] 



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

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

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

 stems and bi-anches (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 siuface as granular tlireads, very often incomplete. The septa 

 are very irregular in length, being frosted granules 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 clavaria. But it obviously belongs to the unknown West Indian forms, 

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

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

 swollen tips are chiefly flattened (see remarks under P. Guadahtpe J, p, 43). 



