30 MADREPORAKIA. 



The calicles are small, 0*75 to 1 mm., very uniform in size and appearance on the 

 different specimens, moderately deep, except at the edges where they may be entirely 

 superficial. The walls consist of a single stout irregular thread, only faintly zigzag, and with 

 a slightly serrated edge, the processes being echinulate or smooth. The septa vary greatly in 

 thickness and size ; they project from tlie angles of the zigzag walls as short processes with 

 very jagged or echinulate tips. Deep down they unite into a tangle, so loose that the base of 

 the calicle seems as if it remained open. From this tangle a varying number of conspicuous 

 pali arise, in deep calicles half way up the walls, in shallow ones to the surface. 



The author of the original description found this coral to be quite distinct from the 

 Brazilian form described by Verrill under the name of Porites solida (see last heading), and in 

 this Dr. Vaughan agrees,* therein adding one to the very limited number of species, wliich, 

 following Dr. Gregory, he allows to the West Indian Porites.^ 



The original figure shows the coral to be, in its structure, quite characteristic of the 

 Atlantic and West Indian Porites, but not one of our astraeoid group (see p. 142). 



Group m — WEST INDIAN ISLANDS PROPER. 



[Exc. The Bahamas, for wliich see p. 76.] 



7. Porites Cura5oa 1. (P. Curagoce prima.) 

 (PL XVII., fig. 3.) 



Syn. Corallium poris stellatis, . . . Seba, Thes. (1758) pi. cix. fig. 11. 



Description. — The corallum rises into a loose, open and irregular tangle of stems and 

 branchlets, 9 cm. high and 14 cm. across. The forkings are at very irregular distances apart, 

 sometimes as much as 3 cm., at others under 2 cm. This and the fact that the angle of 

 forking at the terminals is larger than a right angle (though this lessens with the growth 

 and thickening of the prongs) cause the stock to be wide, open and straggling. The longer 

 nodes between the forkings vary greatly in thickness, J quite irregularly, some less than 1 cm., 

 others, even high up in the stock, may be as much as 1*5 or even 2 cm. thick. These 

 differences appear to be due to the fact that the forking produces prongs of different sizes and 

 thicknesses. The stems are smooth and nearly round, and the prongs are blunt and round- 

 topped. The living layer extends right to the edges of the explanate base. 



The calicles are said to have been densely crowded, mostly round, but sometimes 

 rhomboidal, and distinctly sunk {poris stellatis). The walls appeared somewhat swollen. 



The colour was greyish with a tinge of yellow. 



♦ Bull. U.S. Fish (Commission, ii. (1901) p. 317. j See the Historical section, p. 11. 



X See Morphological section, p. 17. 



