148 



CCELENTEEATA 



O. diffusa Lam. (Fig. 242). Colony very much branched, the 

 branches forming an angle of about 30; cups 3 mm. in diameter: North 

 Carolina to Florida, often common in shallow water. 



FAMILY 3. ASTR^IDAE. 



Usually colonial corals with the zooids so crowded that there is 

 little or no space between them, and in some cases being confluent; 

 colony compact and massive or erect; a few species are solitary: hun- 

 dreds of genera and species, be- 

 ing the largest family of corals. 

 1. ASTRANGIA Edwards and 

 Haime. Colony incrusting, the 

 zooids being distinct and more 

 or less isolated, with 6 septa of 

 the 1st cycle, 6 smaller ones of 

 the 2nd, and incomplete 3rd and 

 4th cycles: 4 American species. 

 A. danae Agassiz (Fig. 243). Colony small, containing from 5 to 

 30 individuals, incrusted on stones, shells, etc., up to 10 cm. in diameter 

 and 5 cm. high: Florida to Cape Cod, in shallow water; common. 



2. ORBICELLA Dana. Colony usually massive with zooids distinct 

 and separated by deep concave spaces: numerous species. 



Fig. 243 Astrangia d<mae (from Davenport), 



Fig. 245 



Fig. 244 Orblcella annularis (Vaughan). 

 Fig. 244 ^^g^ Fig. 245 Meandrina meandrites (Vaughan). 



O. annularis (Lamarck) (Fig. 244). Colony globose; cups 2 mm. 

 in diameter with 12 septa of the first and 12 of the second order : Florida 

 and the West Indies. 



3. MEANDRINA Lamarck. Zooids confluent; tentacles, mesenteries, 

 and septa arranged in rows ; the mouths of the polyps distinct : numerous 

 species. 



M. meandrites (L.) (Fig. 245). Colony 4 to 8 cm. or more long 

 and half as broad with a single large main groove and large septa; 

 columella present: West Indies and Florida. 



