WEST INDIAN ISLANDS PORITES. 67 



the surface, the filaments of the wall reticulum change into flakes. From the surface of the 

 wall knobbed strands arise, some of which slope downwanls into the fossa as septa. Such 

 septa always appear as if they ran up into the walls ; ordinarily the septa appear as vertical 

 rows of knobbed points, sometimes fusing together in pairs. The columellar tangle is large 

 and compact, with or without central tubercle, and surrounded by a ring of small, deep, inter- 

 septal loculi. 



The skeletal elements are not smooth, but tend to be angular and slightly frosted. 



This astraeoid Pontes is preserved as No. 187c in the Paris Museum as P. astrceoides. It 

 is of special interest to us, for it affords the most striking illustration of the principle formu- 

 lated above, see p. 15. We have described hemispherical forms with hemi.spherical eminences, 

 and here we have a sharply jagged form with jagged eminences. This description is taken 

 from my notes and very rough pencil sketch ; the latter hardly allows me to describe the 

 eminences exactly ; still so much is clear that this form is a striking illustration of our 

 principle. 



JAMAICA. 



No true Pontes from Jamaica has, so far as I know, been yet described. The Porites 

 reusdana of Duncan * from the Upper Clarendon Beds — for an account of which see below, 

 p. 159 — is, as Dr. Vaughan suggested,! a Litharcca ( = Goniopora). 



Eecords of branching forms occur. For instance, Duerden { mentions the occurrence of 

 two forms, one growing especially in areas covered with the sea-grass Thalassia in Bluefields 

 Bay, and the other on the shallow parts of the " actual reef " at the same locality, greyish, very 

 brittle, growing in clumps. It is quite possible that no description of them was thought 

 necessary, because, according to the prevailing • view, they would be thought to belong to the 

 two imaginary species furcata and clavaria. 



Group IV,— WESTERN SHORES OF THE GULF OF MEXICO. 



53. Porites Belize 1. (P. Belizei prima.) (PI. IX. fig. 1.) 



[Belize, colL M. Bocourt ; Paris Museum.] 



Description. — The corallum appears to rise as a thin, short, central stem, about 1 cm, 

 thick. The forking or branching is very divergent, at angles of about 90°, the branches being 

 cylindrical or slightly flattened. There is an. appearance of the terminals being represented by 

 irregular tufts of three mammillate branchlets, 7 to 8 mm. thick. The living layer is 4 cm. 

 deep. These stocks fall over and form a tangle from wliich new stocks develop. 



• Quart. Journ. Geol. Soc. xxi. (1868) p. 8. 

 t Bull. Mus. Comp. Zool. xxxiv. (1890) p. 260. 

 } Joum. Inst. Jamaica, ii. (1899) p. 619. 



K 2 



