152 A. E. Verrill — Bermudian and West Indian Reef Conds. 



or hexagonal, usually with a definite, raised, acute or subacute bound- 

 ing wall between them, which may show as a thin zigzag line between 

 the ends of the septa. Usually 3 or 4 rows of synapticulae show on 

 each side of the wall, between the septa, with conspicuous loculi 

 between them. 



The septa are in five cycles, the last cycle being incomplete. 

 There are usually, in well formed calicles, 50 to 64 septa ; the aver- 

 age number being about 58. But specimens often occur in which 

 the number seldom exceeds 48 or 50. 



The septa are finely serrulate and pretty even in height, though 

 those of the different cycles can easily be distinguished by the gra- 

 dations in breadth and thickness. Those of the last cycle are thin 

 and often bend toward and join those of the preceding cycle. The 

 columella is small, at the bottom of a small central pit. It usually 

 consists of about 3 to 6 unequal papillae. 



It is very common on the Florida keys and reefs and throughout 

 the West Indies. Also at Colon, Col. (variety nitida) ; and at the 

 Bermudas (variety ?). It is hardy and can live in muddy situations, 

 and where exposed at low tide, like S. radians, though it seems more 

 partial to the reefs. 



The Bermudian specimens that have been referred to this species, 

 so far as I have observed them, are not of the typical form, and mzj 

 be an extreme variety of S. radians. The calicles are not so large 

 nor so deep as in the Florida form, nor are the septa so numerous, 

 (about 42-48), 



Var. nitida V., nov. Plate xxx. Figure 3. 



The Colon specimens (Yale Mus.) are convex, encrusting plates. 

 Their calicles are not quite so large as in the typical forms, and are 

 much more shallow, while the bounding walls are less distinct, lower, 

 and more rounded, so that the calicles seem less angular and more 

 blended. The septa are numerous (about 50), crowded, and rather 

 equal, giving the calicles a neat and even appearance. No. 1028. 



When well grown this species seems quite distinct from S. radians. 

 It has decidedly larger, deeper, and more angular calicles, which 

 have more elevated and distinct walls. Usually there are about 5, 

 sometimes 6, calicles to 2 centimeters, When in rows. The septa are 

 more numerous (usually 50 to 60) and more equal in elevation. 



But impoverished specimens occur, which are not always easy to 

 distinguish from some of the varieties of S. radians. 



For the reasons for retaining Slderastrcea as the name of this genus, 

 see above, pp. 88, 89. 



