1863.] DUNCAN WEST INDIAN COEALS. 451 



known in the present Caribbean Sea and in the Indian Ocean and 

 Red Sea. Singularly enough, the fossil San-Domingan species is 

 more closely allied to D. porcata and D. uva of the Indian and Red 

 Seas than it is to D. Stohesii, D. Cassiopea, and D. pulcherrima of the 

 sea around Cuba and St. Thomas. 



Agaricia agaricites and A. undata are common both in a coral- 

 breccia in the San-Domingan shales as well as in the West Indian 

 seas. The genus dates from the Cretaceous period, occurring in 

 rocks of that age in France; it has a very wide distribution in the 

 present day, and is found subfossil by the side of the Red Sea. 



Cyphastrcea costata, found in the Barbuda limestone, occurs also 

 in San Domingo ; a slight variation exists in the wavy course of the 

 exotheca, but this forms no specific distinction. The genus is dis- 

 tinguished from Astrcea by the imperfect condition and cribriform 

 appearance of the septa, and the condition of the septa in A. ForsTcce- 

 lana shows the close relation of that species to the Cyphastrcece. The 

 correlation of growth between certain parts of the sclerenchyma of 

 compound Astraeans is as yet little understood ; but thick septa and 

 large columellae are usually found associated with thin walls and 

 slender costae, whilst thin septa, thick walls, and large costae are 

 common ; it is, therefore, quite possible that the thick walls, great 

 costae, and well-developed endotheca and exotheca may have a signi- 

 ficance with regard to the cribriform septa. There are recent spe- 

 cies in the Caribbean and East Indian seas. 



III. Jamaica. 



There is a general relation between the fossil Corals of Jamaica 

 and of San Domingo, and several species are common to both islands. 

 Cyphastrcea costata, common to Barbuda and San Domingo, is found 

 also in the Tertiaries of Jamaica ; and Alveopora Dcedalcea, fossil in 

 San Domingo and Antigua, but recent in the Pacific, is a common 

 form in the hard, white Tertiary limestone. 



Porites is represented in Jamaica by a fossil species related to the 

 recent forms in the Caribbean Sea. 



The great Monilivaltia ponderosa of the Guadaloupe Miocene is 

 found in Jamaica and also in San Domingo ; moreover Placocyathus 

 Barretti is a prominent Jamaican form. 



A very remarkable Placotrochus with a lateral erosion is peculiar 

 to this island, and a species of Thysanus also. As in considering the 

 species from Antigua and San Domingo, Corals were noticed allied 

 to forms in Secondary European strata, so in Jamaica Astroccenia 

 decaphylla (the Astrcea decaphylla of Michelin, from Gosau and 

 Corbieres) is found in an admirable state of preservation. 



The new species of Siderastrcea in the British Museum is a tall 

 and massive form, well worthy of the name " ' grandis" Doubtless, 

 as more specimens are obtained, the Corals will determine the age of 

 the Tertiaries lying upon the Chalk in this island. 



