64 MADREPORARIA. 



see pp. 81 and 82. Tlieir growth-forms are quite different from tliis. Indeed, it seems to me 

 that the method of growth shown by this coral illustrates a type of growth-form distinct 

 enough to be used for purposes of grouping according to growth-forms ; see for example 

 Introduction, p. 19, also Table III. p. 136. 



The differences between the calicles are more subtle and difl&cult to describe, yet if the 

 description given on p. 81, of the calicles of Lamarck's type specimen, is compared with that 

 given above, it will have to be admitted that they cannot be arbitrarily ignored. That this is 

 a distinct " local form " we can gather from Dr. Vaughan's words " there are no indications in 

 these specimens * of an intergradation with forma furcata," that is, with another branching 

 form belonging to the same locality, see below, and p. 11. 



49. Porites Porto Rico 4. {P- Porti-Riconis qvMrta.) 



[Culebra, Ensenada Honda, coll. U.S. Fish Commission, 1898-99 ; Washington.] 



Syn. "Porites jmites forma /ttrmto Lamarck," Vaughan, Bull. U.S. Fish Commission for 1900, ii. 

 (1901) p. 316, pi. XXX. and xxxi. fig. 1. 



Description.^ — The corallum forms dense, roughly convex tangles of usually cylindrical 

 stems, from 10-12 mm. thick, somewhat closely packed, but with a comparatively small amount 

 of fusion between them, for the wavy or zigzag stems remain free far down into the mass. 

 This waviness is due to the fact that the forking does not always result in the formation of 

 two prongs. One only develops where there is room for it, the others merely forming " knee- 

 bends." In the centre of the stock, which may rise to about 18 cm. in height (with 26 cm. 

 width), the living layer is only about 3 • 5 cm. deep, the stems being here most crowded. At 

 the sides, where they are more straggling, the living layer may extend to about 5 cm. The 

 dead parts are covered with white epithecal films, which sometimes appear to have free edges. 



The calicles appear to be about 1 • 5 mm. in diameter. The walls are slightly raised, incom- 

 plete and straggling on the younger parts of the coral at the tips. PHsewhere they appear to be 

 only slightly zigzag, often straight, and then with slight swellings which are quite insignificant 

 in size as compared with the irregularly round or oval granules which represent the septal 

 granules near the wall. These are very irregular in size and shape, and also very irregularly 

 joined to the wall, either by short thick waists or by thin plates. The same irregularity is 

 seen in their junctions with the pali, which are also exceptionally large iixegular granules. 

 When the pali are very large the septal granules are small, and vice vcrsd. Hence the 

 symmetry of the calicles is very much obscured by the varying sizes and irregular junctions of 

 the granules which fill it up. There are usually five pali and a central tubercle, irregularly 

 developed, sometimes absent. 



A cross-section shows trabecular and horizontal elements about equally developed, but 

 very irregularly, here with large meshes, there with small. 



This account of the calicles is based upon the enlarged photograph given by Dr. Vaughan 



' Five were collected. \ See footnote to last heading. 



