WEST INDIAN ISLANDS PORITES. 39 



may be as much as 1 • 5 cm. thick, and the spurs 1 • 2. Pieces of stem occiu- 9 cm. in length 

 without any spur, and the tapering tip above the topmost mammillate-like spur may be 5 • 5 

 cm. long and • 5 cm. thick at the rounded apex. Depth of living layer appears to have been 

 great, over 12 cm. 



The calicles were 1 • 5 mm. in diameter, shallow funnel-shaped. The walls, somewhat 

 obscured, appear as if they were sharp, obtuse-angled ridges between the calicles and show 

 skeletal elements varying greatly in thickness, here swollen and thickened, there very 

 tjiin. The septa are also very variable in texture ; they are conspicuous, some thin, others 

 thick, or broad and flaky, each one varying along its own length ; laterally they are notched 

 rather than echinulate. The pali appear as large rounded knobs. 



The section shows rather a thick, axial layei' of somewhat close streaming reticulum of 

 stout threads, passing very gradually into a faii-ly regular radial and concentric system of 

 stout elements, yet with conspicuous oblong pores, so that the whole section is open reticulum 

 without any part solidified. 



The growth-form of this fossil Porites is so far unique. The fragments might easily have 

 been taken at first sight for those of Madrepora, but fortunately the calicles, though mostly 

 coiToded, can here and there be made out, and leave no doubt but that it is a true Porites. 

 Its spur formation can be easily deduced from the typical forking. One prong stands out as a 

 spur and aborts while the other carries the stem continuously onwards with hardly a curve. 



The nearest Porites to this as to its growth-form would probably be P. Java Sea 2 (Vol. V. 

 p. 189, PI. XXVIII. fig. 8, PI. XXIX. fig. 2) ; the sharp thin tapermg stems belong to both, 

 but unfortunately we do not know what the complete stock of this coral is like. Certaialy 

 neither the branching of P. Java Sea 3 nor its calicles show any resemblance to those of this 

 coral. 



a. Five fragments. Geol. Dept. E. 2551. 



17. Porites Barbados 7. (P. Barbatce septima.) (PI. IX. fig. 2, left hand figure.) 

 [Barbados (Pleistocene), coll. Franks ; British Museum.] 



Description. — The corallum rises in erect stems, fau-ly uniform in thickness, and either 

 forking at small angles (30°) or rising zigzag owing to incipient but abortive forking, one 

 prong remaining as a knee-bend or short process. These forkings or attempts at forking are 

 at fairly regular distances, 2 cm. apart. The depth of the living layer was at least 5 cm. 



The calicles have all been worn down but are plainly visible in section where the sm-face 

 is not abraded down to the axial streaming reticulum. They are slightly over 1 mm. in 

 diameter. The skeletal elements forming a rather close reticulum, the walls, septa and colu- 

 mellar tangle, varying veiy much in thickness, here swollen, there thin, but the calicle 

 symmetrj' is traceable here and there, and even the number of the paU, six, can be made out. 



The section shows a very large axial strand, loose, open, and almost as much filamentous 



