426 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 6, 



calices are a little smaller than in the European form. There is no 

 specific difference. 



Coll. Geol. Soc. and Brit. Mus, 



20. Rhodar^a irregularis, spec. nov. 



Corallum massive and tall. Corallites long, irregularly prismatic, 

 crowded, distinct ; diameter -A- inch. Walls irregularly reticulate, 

 delicate. Septa in six systems of three cycles ; sometimes a fourth 

 is seen ; they are tolerably well developed and sublamellar. Pali 

 very distinct before the primary and secondary septa. Columella 

 formed by the junction of the pali. 



The specimens are much altered by fossilization, but the struc- 

 tural details enumerated above are evident enough. The species is 

 distinguished by the mass of pali and the presence of an incomplete 

 fourth cycle. There are no recent West Indian species of this genus, 

 those known being either Chinese or from New Holland ; the fossil 

 form is from Dax (Miocene). 



Prom the Marl-formation of Antigua. Coll. Geol. Soc. 



21a. Alveopora Djedaljea, Blainville, var. regttlaris. PI. XIY. 

 figs. 4a-4:c. 



Corallites prismatic, in all cases radiating from a small base, and 

 lobed above. Walls very regularly perforated and thin. Calices 

 a little smaller than the transverse sections of the corallites, rather 

 deformed, polygonal; \ line in diameter. Septa spiculiform, and 

 forming a false columella by their junction with some slight cellular 

 trabecule. 



Erom the Chert- and Marl-formations of Antigua. Coll. Geol. Soc. 



21b. Yar. minor. 



A small variety from the Chert of Antigua. Coll. Geol. Soc. 



22. Alveopora microscopica, spec. nov. PI. XIY". fig. 5. 



Corallites barely -±j inch in diameter, prismatic and hexagonal, 

 tall. Walls with reticulations, rendered less regular and equal than 

 in the above species by the rather wavy track of the large longitu- 

 dinal sclerenchymatous threads and by their irregular thickness. 

 Septa small, less spiniform than in other species ; usually twelve in 

 number. 

 . Erom the Marl-formation of Antigua. Coll. Geol. Soc. 



23. Alveopora fenestrata, Dana. 



In fronds. From the Marl-formation of Antigua. Coll. Geol. Soc. 



II. San Domingo. 

 1. Brachtcyathus Henekeni, spec. nov. PI. XY. fig. 1. 



The numerous small simple Corals considered to belong to this 

 species are all young, and in examining them allowance must be 

 made for the rapid growth which takes place in their breadth after 

 a certain height has been attained. Corallum simple, straight, with 



