i mm deep, bounded by thin plates of original thecae. 

 Septa iO-i2 per cm, 6 or 7 meeting columella, notch 

 in septum simulates palijorm lobe. Slightly exsert, 

 rarely meeting in colline groove. Columella rudimen- 

 tary, columellar centers sometimes connected by thin 

 toothed septal lamellae. Costae on non-calicinal surface. 



27. Colpophyllia natans (Muller), (Plate 18). 



Described by Matthai (1928) pages 101-107. 



Large, light convex mass. Valleys more or less inter- 

 connected and winding, shallower than C. amaranthus. 

 Wall grooved as in C. amaranthus. Valleys green, 

 walls brown. Florida, Bahamas and West Indies. 



Large massive, vesicular, light convex masses. 5Vo 

 stalk. Valleys sinuous, usually continuous, width i5-20 

 mm up to 30-40 mm at edge, depth up to 17 mm, 

 average a, shallower between centers. Colline thick- 

 ened at base to 22 mm, average 17 mm. Septa 8 or 9 

 per cm, 5 or 6 meeting columella. Otherwise similar to 

 C. amaranthus. 



28. TAanicina areolata (Linnaeus), (Plates 19,20,21) 

 Described by Matthai (1928), pages 80-91. 

 Yellow to brown with greenish valley, tentacles 



transparent, with white tips. Form varies, usually 

 roughly oval with narrow ends and flattish upper sur- 

 face and converging to a short stalk below. Never 

 more than about 6 inches long. Valley branches out 

 into side arms, up to one inch wide. Septa seen under 

 lens have fine holes, about 18 to the centimeter and 

 thinner than in ?d. mayori. Very common in Florida, 

 the Bahamas and the West Indies in shallow water. 



Corallum narrow towards ends, small. Upper sur- 

 face \lat or convex, sometimes lobular, underneath with 

 central short stalk. Valley continuous with median 



86 



