GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 437 



tional specimens of S. pariana and S. confusa from. St. Croix, Trinidad, 

 are needed before those species can be adequately characterized, but 

 the original descriptions of them are included. Therefore, the fol- 

 lowing old names are adopted in the discussion here given : 



S. radians (Pallas), living. 



S. siderea (Ellis and Solander), living; fossil in the Miocene Bowden 

 marl of Jamaica and hi deposits of similar age in Santo Domingo and 

 Cuba. 



8. stellata Verrill, living. 



S. conferta (Duncan), fossil. 



S. pariana (Duncan), fossil. 



S. confusa (Duncan), fossil. 



I am describing as new five species and one variety as follows : 



S. pourtalesi, upper Oligocene or lower Miocene of Santo Domingo. 



S. pliocenica, Pliocene Caloosahatchee marl, Florida. 



S. hillboroensis, lower Miocene Alum Bluff formation, Florida; 

 Oligocene Chattahoochee formation. 



S. silecensis, Oligocene Tampa formation, Florida, and Chatta- 

 hoochee formation, Florida and Georgia; lower Miocene, Alum Bluff 

 formation, Florida. 



S. dalli, Pliocene Caloosahatchee marl, Florida. 



These species may be divided into five groups on the basis of the 

 number of septa. The first group has only three cycles of septa and 

 contains one species; the second group has the fourth cycle of septa 

 incomplete; the third normally has four complete cycles and occa- 

 sionally a few quinaries ; the fourth has uniformly a few quinaries in 

 fully developed calices; the fifth has from 12 to 43 quinary septa in 

 fully developed calices. The following synopsis of some striking 

 characters may aid in recognizing the different species : 



SYNOPSIS OF CHARACTERS OF SPECIES OF SIDERASTREA. 



Only 3 cycles of septa 1. S. pariana (Duncan). 



Fourth cycle of septa incomplete. 



Columellar fossa a pronounced pit. 

 Calices rarely 4 mm. in diameter. 



Columella composed of from 1 to 3 fused papillae. 2. S. radians (Pallas). 

 Calices deformed, lesser diameter 2 to 3 mm., length as much as 6.5 mm., or 

 more. 



Columella finely papillary 3. 8. stellata Verrill. 



Columellar fossa only moderately deep. 

 Calices 2.5 to 5 mm. in diameter. 



Columella false 4. S. confusa (Duncan). 



Columellar fossa shallow, calices shallow and open. 



Wall delicate, interseptal loculi relatively open. 5. 5. pourtalesi, new species. 

 Wall stout, interseptal loculi narrow, largely closed by granulations and 

 syapticulae (fourth cycle complete in some large calices). 



6. S. pliocenica, new species. 



