UNKNOWN ATLANTIC OR WEST INDIAN PORITES. 97 



85. Porites West Indies x. 20. (P. Americana ineertee sedis vieeaima.) 

 (PI. V. fig. 9 ; PI. X. fig. 2.) 



[British Museum.] 



Description. — The coralhim rises into small clusters of short, thin, waving, gradually 

 thickening branches, here somewhat flattened, there swollen or slightly constricted, and 

 varying from about 8 mm. to 1 cm. in thickness. The forking shows signs of irregular 

 dichotomy, but at very small angles, the prongs bending up into the vertical. Before dividing, 

 they are frequently flattened so as to be oar-shaped, with level top ridges 6 mm. thick and 

 1 • 1 cm. long. The living layer is from 2 to 2 5 cm. deep. Epithecal films encircle the dead 

 stems. 



Tlie calicles are small and, when round, about 1 mm. in diameter and under, but they are 

 mostly drawn out of sliape, as if tlie polyps had strainofl upwards. Tlie apertures open 

 obliquely at the surface, and their shapes are lengthened out in the direction of growth. 

 Except at the growing tips, the walls are flush with the surface. The tall, thin, sparsely 

 perforated membranes, which rise funnel-shaped round the calicles at the tips, change into 

 ragged-edged twisted flakes sending out knobbed processes as so many irregular septa, which 

 together with the columellar tangle and pali, seem to fill tlie cahcle with a ragged ili.sordered 

 network showing but little radial symmetry. Tlie septal formula can just be made out, the 

 pali being small rods or granules. The flakes in the younger calicles are mostly confined 

 to the walls, but in the older calicles they gradually extend over the whole intra-calicular 

 skeleton. 



The colour of the unbleached coral is a rather warm buff, with here and there a faint 

 reddish tinge. 



The section shows the open axial reticulum of stout lamellai passing outwards into a much 

 denser but irregular cortical layer. 



This Porites is another example showing the same type of growth as that last described. 

 See Table III. E d, p. 136, for the forms whose stems thicken as they rise. This one is unlike 

 any yet recorded, and it is unfortunate that its locality is so far imknown. 



a, b. Two small portions of stocks, one bleached. Zool. Dept. 1906. 1. 1. 6. and 7. 



86. Porites West Indies x. 21. (P. Americana inccrta; sedis prima et vicesima.) 

 (PI. VI. fig. 1 ; PI. XV. fig. 4) 



[West Indies, coU. J. Poland ; British Museum.] 



Description. — The corallum rises as a stout stem, 2' 5 to 3*5 cm. thick, from nearly the 

 whole surface of a small basal disk, some 4 cm. in diameter, and with cushion-like edges 1 cm. 

 thick, the edges curving upwards on to the stem. The basal disk — or enlargement of the stem — 







