WEST INDIAN ISLANDS PORITES. 33 



form has some resemblance to that of P. West Indies x U, which, however, was still young. 

 It is otherwise unique. 



The boldness of the calicles is also a feature of interest. 



We have then clearly three tUfferent types of Pontes from Cura^oa alone, which cannot be 

 easily brought into the species scheme mentioned in the Introduction, p. 10. 



It is not at all likely that this list exhausts the Porites fauna near Curacoa. Fossils 

 occur in the young Quaternary strata of this and of the neighbouring island Arube. These 

 represent the remains of both branching and encrusting or massive forms.* 



10. Porites Trinidad 1. (P. Trinitatis prima.) (PI. I. figs. 5a, 5i.) 

 [Savannah Grande (Eocene t), from the coll. Mus. Pract. Geol. ; British Museum.] 



Description.— Ti\e fossil shows that the corallum was massive, built up continuously by 

 long, straight trabecule, very thick and joined by tliick, short, horizontal elements. The 

 junctions of the horizontal and vertical elements are swollen like rows of large rounded beads, 

 which run straight along the trabecule, but are arranged in more or less wavy lines along 

 the horizontal elements. These beaded trabecule are so thick that only three go to the 

 millimetre. 



The calicles, only seen in section, are about 1-25 mm. in diameter and show an UTegular 

 wall thread of thick, smooth, skeletal matter with either stout, smooth septa or rounded 

 granules, according to the position of the section. A confused central tangle, quite iiTCgular, 

 consisting of but a few strands can be made out, with no clear traces either of pali or of 

 columellar tubercle. 



This fossil is of great interest. The great thickness of the skeletal elements is, as we have 

 seen (cf p. 13), one of the characteristics of the West Indian Porites. Here this character 

 seems to have been exaggerated, perhaps by secondary alteration dming fossilisation, although 

 the symmetry of the whole seems to preclude the idea of much change of that kind. The fact 

 that it was a massive form leads us naturally to associate it hypothetically with the astrseoid 

 type (p. 142) of glomerate forms occurring in the West Indies. This suggestion finds con- 

 firmation in the absence of all traces of pali in the sections. It is possible, therefore, dimly 

 to reconstruct the surface aspect of the calicles, with their deep, open fossae with short, nearly 

 uniform septa, only fusing deep down with a columellar tangle. 



A study of the mass shows that great numbers of organisms were incorporated in it 

 as it grew in thickness, and further that the skeletal elements were not seldom hollowed out 



• Vaughan, Sammhingen des Geologischen Reichs-Museum in Leiden, ser. ii. bd. ii. (1901) 



heft 1. 



t Mr. Spencer (Quart. Journ. Geol. Soc, Iviii. (1902) p. 357), while quotmg Dr. Guppy and 

 Prof. Gregory as claiming the Naparima beds as Eocene formations, thinks them to have been some- 

 what earlier. 



