88 MADREPORARIA. 



75. Pontes West Indies r. IQ. {!'. Americana inccrtw scdis decima.) (PI. XIV. fig. 3.) 



[Paris Museum.] 



Description. — The coralluin rises into a compact clump of short, thick, knarled branches, 

 apparently produced by the forking of a stem at small distances, that is, at about every 

 • 5 cm. apai-t — and at considerable angles. The prongs are short and round. The stem and 

 branches are too irregular to measure, but appear to be about 1*8 cm. thick. 



The calicles are • 75 mm. in diameter, rather deep. The walls are thin and steep. The 

 internal skeleton is irregular and rather deep down. The septa are stout, often long, thick and 

 either truncated or joining the pali. The latter rise from a columellar ring as long, thick, 

 coarse, truncated rods ; in the more regular calicles, the five principals can be made out. 

 There are six to eight large, open, interseptal loculi. 



This specimen, No. 182 c in the Paris Museum, has been somewhat distorted by Balanids, 

 but appears also to be referable to the branching West Indian forms, and to be one in which 

 the forkings take place in rapid succession. 



76. Porites West Indies .':. H. (P. Americana incerkv scdis imdecima.) 

 (PI. XV. fig. 2.) 



[Paris Museum.] 



Description.. — The corallum ri.ses into open tufts of short, flattened, angularly twisted 

 branchlets. The tips seem to I'ork at very wide angles, the terminals being also flat and 

 angular. The living layer is 4 cm. deep. Epithecal films creep over dying edges. 



The calicles are 1 mm. in diameter, everywhere depressed, of irregular outline, either very 

 angular or subcircular. The wall-thread is hardly visible, though the walls themselves look 

 stout, being thickened by the large granular bases of the septa. Tlie septa themselves often 

 project from the walls — short, thick, swollen and truncate — sometimes united together to form 

 an inner synapticular ring. The five principal pali are arranged in a large circle, somewhat 

 below the surface and surrounding either a small, deep, open fossa or a central tubercle. 



The skeletal elements are generally coarse and thick. 



The forking of tliis specimen, No. Z 182^ of the Paris Museum, is again irregular and the 

 order of it difficult to make out. The result certainly presents us with a new type of growth- 

 form which appears to be deducible from the more regular type by variation in the methods of 

 forking and the shapes of the terminals. The specimen requires closer study. It is placed 

 here because its gi-owth-form may be regarded as a variation of the dichotomous branching 

 of the West Indian I'urm.s, and it is one of the Paris Museum specimens labelled " clavaria." 



