70 MADREPORARIA. 



irregular, columellar tangle. The interseptal loculi are consequently very irregular in size and 

 an-angement, there being generally one or two much larger than the rest. 



In section, the network shows as a fairly close streaming of fine trabecular elements. 



This and the coral last described are typical encrusting forms of the astrseoid type. 

 Tliey are interesting for two reasons : first, they both show very clearly the growth-principle 

 pointed out on p. 15, the mounds repeating the shape of their stocks, cf. the figures 7 and 

 la on Plate XVII. ; and secondly, that though they are both typical of those Forites usually 

 called astrceoides, and are, moreover, from the same locality, they differ very greatly in almost 

 all their most important details. P. Belize 3 differs from 2 in its oval outline, its soft woolly 

 surface, its reticular walls, and irregular radial symmetry, whereas P. Belize 2 is hemispherical, 

 with hard-looking surface, sharp-ridged walls and pronounced septa. Both have pronounced 

 trabeculae, but in the one case crowded, in the other far apart. Both have a straggling 

 columellar tangle and very irregular interseptal loculi, but the calicles in the second specimen 

 are somewhat shallow over the whole stock. There is indeed, hardly a structural feature 

 which, when closely looked at, is the same in both. Belated the two forms undoubtedly are, 

 but we do not know how. 



a. Zool. Dept. 57. 12. 16. 2. 



VERA CRUZ. 



From Vera Cruz come records of Pontes, but so far no descriptions that I have found. 

 An explanate form, 10 cm. longest diameter, mammillated owing to its being crumpled and 

 folded, but in reality, apparently not more than 5 to 6 mm. thick, was found on the Caletta 

 reef in the harbour. It was growing on an anchor which had been five years in the water.* 



Other massive forms called astrceoides are said to be abundant among massive corals of 

 other genera in the inner waters. 



Branching forms are found in fragments in great quantities on the shingle of the Islands 

 Verde and Sacrificios, but the actual grounds where they grow were not discovered. These 

 fragments are said to be of " Porites furcata.\ 



• See Heilprin, Proc. Acad. Nat. Sci. Phil. (1891) p. 75. The author, calculating the thickness 

 alone, suggests that the rate of growth would therefore have been only 1 • 25 mm. in a year — that is 

 in thickness. Explanate forms are those in which the growth is most active round the edges, 

 while the centre remains nearly stationary. We have clearly to distinguish between the growth of 

 individual polyps and the growth of the colony by budding. The author's calculation refers chiefly 

 to the former growth ; the latter is of course much greater, and was nearer 2 cm. annually in this 

 case. 



t Id., op. cit. (1890) p. 303. 



