88 MADREPORARIA. 



75. Porites West Indies x. IQ. (T. Amo-icatm iiwertoc sedis dedma.) (PI. XIV. fig. 3.) 



[Paris Museum.] 



Description. — The corallum 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. apart — 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 pah. 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 x. H. (P. Americana incertce sedis undedma.) 



(PI. XV. fig. 2.) 



[Paris Museum.] 



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

 branchlets. The tips seem to fork 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. The septa themselves often 

 project ft-om the walls — short, thick, swollen and truncate — sometimes united together to form 

 an inner synapticular ring. The five principal pah 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 this specimen, No. Z 182 17 of the Paris Museum, is again iiTegular 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 growth-form may be regarded as a variation of the dichotomous branching 

 of the West Indian forms, and it is one of the Paris Museum specimens labelled " clavaria." 



