1863.] DUNCAN—- WEST INDIAN CORALS. 447 



extracalicular gemmation; in this it resembles the recent Astrcea 

 Pleiades; moreover it would appear that one of the varieties of 

 Astrcea crassolamellata does so likewise. 



Astrcea radiata, var. intermedia, connects the fossil Astrcea endothe- 

 cata with the recent Astrcea radiata of the Caribbean Sea ; and Astrcea 

 costata has a close affinity with the recent Astrcea cavernosa of the 

 West Indies. 



Astrcea Barbadensis, which is common to the Marl-formation of 

 Barbadoes and Antigua, has a close affinity with Astrcea annularis 

 of the Pacific, but differs from all the known recent West Indian 

 forms. 



Astrcea Antiguensis is a well-marked species and a very fine form ; 

 it has many structural affinities with Astrcea endoihecata, and to a 

 slight extent with Astrcea cavernosa. 



There are two species of Isastrcea, one of Astroccenia, and one of 

 Stephanoccenia, at Antigua, 



The range of the genus Isastrcea has been difficult to determine, 

 on account of the state of preservation of some Corals of the genus 

 Prionastrcea, which would appear to be of Miocene age. The Isas- 

 trcece of the Antiguan beds have a very remote affinity to the 

 Miocene corals formerly called Prionastrcea irregularis, P. diversi- 

 formis, and P. aranea, but a very close resemblance to the true 

 Isastrcece of Tisbury. They are without columellas, and can only 

 be classified under the genus Isastrcea ; one species equals Isastrcea 

 tenuistriata (Inferior Oolite) in the number of its septa, but is a 

 dwarf, its corallites never measuring more than -^ inch across : the 

 other has great resemblances, both in its structure and mode of 

 fossilization, to the Isastrcea oblonga (Portland) ; it is smaller, how- 

 ever, and the septal number is never so complete. 



Isastrcea angulosa, Edwards & Haime (Maestricht), is also closely 

 allied to the Isastrcea turbinata from Antigua. 



The Astroccenia so common in Antigua is found in irregular 

 masses, which present most curious varieties of silicification. The 

 form is hardly separable from Astroccenia ornata (Turin, Miocene), 

 even as a variety, but the typical form is found in small masses. 

 This variety is only remotely allied to the species of Astroccenia 

 from Jamaica, which is the A. decaphylla, a European Cretaceous 

 form. 



The Stephanoccenia tenuis of the oldest beds has not been found in 

 the Marl ; it has only a generic affinity with the species from the Mio- 

 cene of San Domingo, and its alliances with all the known forms are 

 remote ; it approaches Stephanoccenia formosissima and Stephano- 

 ccenia intersepta more closely than it does the Eocene species. The 

 genus ranges from the Jurassic strata to the recent Coral-formations, 

 species having been determined from the Oolite at St. Mihiel, from 

 the Lower Cretaceous strata at Gosau, and from the Eocene ; but not 

 hitherto from the Miocene, though S. intersepta, which is barely sepa- 

 rable from the Gosau Astrcea (Stephanoccenia) formosissima, Sowerby, 

 is said by Lamarck to exist in the American and South Seas. 



The Solenastrcea Turonensis of the Ealuns appears to be represented 



