WEST INDIAN ISLANDS PORITES. 65 



(I.e. pi. xxxi. fig. 1). A comparison of these calicles with those shown on the same coral, 

 pi. XXX., suggests that, as a rule, the calicle skeleton is less crowded with granules. The 

 same irregularity in size and in the joining together of the elements can be seen in both, but 

 it appears as if in pi. xxxi. fig. 1, a part had been photogi-aphed where the skeletal elements 

 had been slightly hypertrophied, owing; perhaps, to excessive crowding in the part to which 

 the fragment belonged. 



While I do not deny that this may not be of the same " species " with Lamarck's P. furcata, 

 it does not appear to me to have the form of furcata. Portions of the type of Lamarck's coral 

 have been illustrated by Milne-Edwards and Haime in their " Monographic des Poritides "* 

 (see also PL XII. fig. 1). The conspicuous features of the older figures are the amount of 

 fusion between the stems, the distinct open fosste, and the marked trabecular texture of the 

 skeleton, seen in sections, and even in side view of the calicles. These are differences which 

 cannot be ignored. With this form compare Plate XIV. fig. 1, which represents No. 182 i in 

 the Paris Museum, from some unknown West Indian locality. 



50. Porites Porto Rico 5. {P. Porti-Riconis quinta.) 



[Porto Rico, coll. Vaughan ; U.S. National Museum.] 



Syn. Porites astrmoides forma a Vaughan, Bull. U.S. Fish Commission, 1900, ii. p. 317, pi. xxxii. 

 and xxxiii. fig. \. 



Description. — The corallum forms hemispherical masses, the lower margins of which 

 may hang free of the supporting mass of previous growth-stages, upon which it is perched like a 

 cap. The surface is raised all over into smaller hemispherical eminences, all reaching to about 

 the same height, and separated by a conspicuous system of deep, narrow valleys. Traces of 

 similar systems, though on a smaller scale, are seen starting upon the eminences. 



The calicles (15 to 2 mm.) are typical of those forms in which the walls are rather 

 regularly reticular, and consist, seen from above, of stout filaments. The median wall-thread is 

 frequently incomplete, so that the septal plates stand up. The septa vary considerably in length, 

 some short and pointed, others longer and knobbed, others again here and there fusing together, 

 so that the typical septal formula of Porites can be made out. There is an irregular columeUar 

 tangle, with a central tubercle which is often flattened in the directive plane. 



This description is based upon Ur. Vaugban's text and excellent photographs. Tlie nidi- 

 ments of a third cycle which he mentions is vary rare in Porites, and requires fresh investiga- 

 tion — a matter always difficult in the case of walls built up of a reticulum, for they are 

 usually so confused that the moi-phological values of the details can no longer be deciphered. 

 I would suggest that the explanation of their presence is that the calicles which show traces of 

 the third cycle are to be associated with double calicles. These happen to be especially 

 numerous in Dr. Vaughan's photograph of his forma yS. 



• Ann. Sci. Nat. xvi. (1851) p. 21. 



