90 MADREPORARIA. 



arrangements of wall- and septal-granules and pali, while beneath this system of surface 

 granules the skeletal elements are arranged as a continuous, open, filamento-flaky network with 

 angular meshes. Tlie pali are very inconspicuous, and the columellar tubercle is very small. 



The sections show an immense axial strand which seems even to thicken in the larger 

 branches and terminals. The surface layer nowhere seems to become dense. The colour of the 

 living layer is a dark blue-grey. 



Tliis specimen is of very great interest. It has, unfortunately, no recorded locality other 

 than " West Indies," and seems further to have suffered from the fact that calcareous worm- 

 tubes run over it. We therefore do not know how far the depth of the colony is normal. 



The branching is not very typical of West Indian forms, although it might easily be 

 deduced by flattening from some pear-shaped initial colony. Among its points we note : (1) 

 the bluish-black colour of the unbleached branches ; (2) the irregular forking with persistence, 

 and even continued growth of thinner prongs ; (3) the calicles, as thin-walled, large, concave 

 depressions ; (4) the tendency of the septa to bi'eak up into echinulate granules ; (5) the 

 feeble development of paH. 



We have here again one more type of growth-form with which systematists will have in 

 the future to reckon and place in their proper series. Such series can only be begun when we 

 have rid the work of phantom species. 



a. Zool. Dept. 39. 3. 29. 10. 



79. Porites West Indies x. 14. {P. Americana incertm sedis quartadecima.) 

 (PI. V. fig. 2 ; PI. XIII. fig. 3.) 



[British Museum.] 



Description. — The corallum rises on a small cylindrical stem, 1 • 5 cm. thick, and forks 

 regularly at about 1 cm. apart, and at angles slightly under a right angle. The prongs, until 

 they flatten and fork, are again about 1 • 5 cm. thick, and cylindrical. The stock is thus squat 

 and thick, but it is not simple, because it appears from a study of the forkings that each pair 

 of prongs is slightly twisted out of the plane which it would have occupied with symmetrical 

 dichotomous forking. These twists seem to follow some regular principle. The living layer 

 is about 3 • 5 cm. deep. 



The calicles are large and uniform, about 1 • 6 mm. in diameter, subcircular and con- 

 spicuous. The wall-edges, which, in the younger parts, are a deUcate, open, crisp network, 

 showing a thin irregularly zigzag wall-thread, gradually cliange into what appear to be 

 continuous, smooth flakes, which, in reality, represent the rapid thickening of the skeletal 

 elements. The short septa, with crisp, echinulate, septal granules at their tips, project boldly 

 from the wall, only meeting together lower down in the general, open tangle, which fills the 

 floor of the calicle. From this the pali arise as star-like, echinulate granules, similar to those 

 at the tips of the septa projecting from the edge of the wall. The symmetry of the interseptal 

 loculi and of the pali is obscured by the crisp, ecliinulate edges of tlie septa and other elements 



