FAMILIES AND GENERA OE THE MADREPORAEIA. 89 



culate, moderately granular laterally. Union of the transverse en- 

 largements of neighbouring septa near the columella often occurs, 

 and gives a paliform appearance. Endotheca and epitheca exist. 



Distribution. — Fossil. Oolite : Europe. Cretaceous : Europe. 

 Miocene : Europe ; W. Indies ; Raised beaches, E. Africa. — 

 Rece7it. Indian seas, E. American seas, Caribbean, Pacific. 



A group of forms possessing very variably-shaped calices was 

 once scattered amongst four genera, namely, Mceandrina, Lmk., 

 I^latygyra^ Ehr., Astroria, Ed. & H., and Coeloria, Ed. & H. 



Milne-Edwards and Jules Haime united the last two genera, 

 abolished the genus Platygyra, and explained the distinct character 

 of Mceandrina. 



Hence in the ' Histoire Naturelle des Coralliaires ' the forms are 

 all placed under the genus Coeloria. This is correct, because the 

 characters of Astroria and Coeloria may be recognized on the same 

 colony. M. de Pourtales notices how difficult it is to distinguish 

 forms of this genus which have very loug calices from Mcean- 

 drincB. He proves that some Coelorice must come within the genus 

 Mceandrina. On the other hand, I have shown that the internal 

 structures of Coeloria pa chycTiil a do not permit it to remain in the 

 genus (Journ. Linn. Soc. vol. xvii. p. 361, 1884). 



There does not appear to be any satisfactory reason for sepa- 

 rating the genera Mceandrina and Coeloria ; and I consider the 

 latter to be a subgenus of the former. But there is no warrant, 

 as the late Dr. Briiggemann (Phil. Trans, vol. clxviii. p. 571) 

 thought, for resuscitating the name Flatygyra, Ehr. 



Subgenus Cceloria, (genus) Milne- JEdwards Sf Jules Ilaime^ 

 Hist. Nat. des Corall. vol. ii. p. 411 (1857). 



Colony massive, light, largely fixed at the base, hemispherical, 

 convex, rarely subplane. The corallites in series are united by 

 their walls, forming simple interserial ridges. The length of the 

 valleys, which are usually deep, varies greatly, even in the same 

 colony, from that of a simple bud in which the calicinal centre is 

 distinct to that of several centimetres. In the series the centres 

 are indistinct. Columella parietal, and formed by trabeculae 

 from the ends of the septa, may be spongy. Septa thin, minutely 

 dentate, and granular laterally. Endotheca abundant. In sec- 

 tions the fused walls are slender. 



Distribution. — Fossil. Miocene: West Indies. — Becent. Eed 

 Sea, East Indies, Pacific. 



