FLORIDAN PORITES. 75 



61. Pontes Florida 6. {P. Flcmdm sexta.) (PI. IV. fig. 1.) 



[Florida Reefs, coll. Agasaiz, Harvard College Museum ; and coll. Thomson, British Museum.] 



Syn. Porites astrceoides Pourtales (? Lamarck), Mem. Mus. Comp. Zool. vii. i. (1880) pi. xvi. figs. 1 to 

 12, 20, 21. 



Description. — The corallum rises into regular, nearly smooth, hemispherical masses, with 

 surface slightly but distinctly convoluted, being covered all over with smooth rounded 

 eminences of different sizes, from 1 to 2 cm. in diameter, and separated by narrow but convex 

 valleys. The living layer extends all round down to the substratum. 



The calicles are deep subcylindrical pits. The walls consist of a stout, smooth, zigzag 

 thread, here and there tending to be reticular and showing a few wall pores. The short, 

 smooth, stout septa project from the wall in such a way as to seem to continue the curving 

 angle of the zigzag ; this looks as if septa and wall-thread had been produced out of one piece 

 by the excision of rounded interseptal loculi. The tips of the septa are slightly swollen. 

 These septal processes descend vertically down, showing no signs of protruding further into the 

 calicle, and ultimately join the close solid-looking tangle, which shows signs of smooth round 

 pores in it, and is separated from the walls by the symmetrical ring of deep, round, interseptal 

 loculi. 



The sections show the pores here quite irregular and there in vertical rows, regular 

 enough to produce trabeculse. 



This description is based upon the beautiful drawings, referred to above, of the original 

 specimen. Two drawings are given of the calicles : in one (fig. 4) the wall-thread and septa 

 are smooth-topped and on the same level ; in the other, the walls are incomplete and the septa 

 appear to be exsert. 



There is, fortunately, a specimen in the National Museum which may possibly be of the 

 same kind, inasmuch as it is from the Florida reefs, and was presented to this Museum by 

 Sir John Murray. But there are differences. It is not hemispherical, having grown up 

 into a ridge on one side, while the other has crept outwards and downwards. The eminences 

 on the ridge are themselves sharp-ridged. The walls are more flaky than is shown in 

 Pourtales' fig. 4. Although the generally lamellate texture of the skeleton, both trabecular 

 and horizontal, is as shown in the sections, figs. 21 and 22, the illustration here given, 

 PI. IV. fig. 1, which is of the Museum specimen, shows the whole skeleton as a very flaky 

 network, it being quite easy to see, except where the wall-edge has risen as a filamentous 

 tangle, that the septa run out as thin sharp points from the edges of flakes. 



These two corals, then, are only provisionally put together ; they agree in the general 

 type of calicle, which is that which is usually known as astr£eoid, but they show important 

 differences in growth-form in that the one is hemispherical with hemispherical eminences, while 

 the other forms somewhat of an irregular ridge with eminences also tending to be ridged. In 

 this latter case, also, the skeletal texture is more flaky. More specimens are needed to see 

 whether these are separate local forms. The Florida reefs might certainly be expected to 

 produce more than one kind of explanate or massive form. 



a. Presented by Sir John Murray, K.C.B. Zool. Dept 91. 2. 3. 36. 



L 2 



