FAMILIES AND GENERA OF THE MADREPOBARIA. 13 



II. Alliance FLABELLOIDA. 



Simple Turbinolidse, fixed or free, with or without rootlets, more or less 

 compressed and flabelliform or cuneiform. Calice elongate elliptical or 

 short. Septa large, exsert or not. Columella parietal. Costse variable, 

 often crested or spined. Epitheca pellicular or membranous. Rarely 

 increasing by deciduous gemmation from the wall. 



Genus Flabellum, Lesson. 



Subgenus Blastotrochus, Ed. & H. 

 Genus Rhizotrochus, Ed. & H. 

 Genus Thysanus, Duncan. 

 Genera absorbed : — 



Vasilium, T. Woods; Phyllodes, Philippi ; Ulocya- 

 THus, Sars. 

 Genus placed as a subgenus : — 



BtiASTOTROCHUS, Ed. & H. 



Genus Elabellum, Lesson, Ilhistr. de Zool. 1831, amended. 



Syn. Vasilium, T. "Woods; Phyllodes, Pbilippi ; Ulocyatlms, 

 Sars. 



The corallum is simple, straight or bent, more or less compressed, 

 fan-shaped. The calicular fossa is narrow and deep, usually 

 long, rarely widely open. The columella consists of a few 

 trabeculse from the inner ends of the septa. The septa are 

 numerous, and reach up to or beyond the wall. The costge may 

 be crested, spined, or simple. The base may be attached or may 

 become free, broad or pedunculate. Eootlets from the wall occa- 

 sional. Epitheca pellicular, rarely dense. 



Distrihution. — Becent. Almost universal. — Fossil. Eocene : 

 Europe, Asia. Miocene : Europe, "West Indies. Cainozoic : 

 Australia and New Zealand. Pliocene : England and Europe. 



This large genus is closely allied to the compressed forms of 

 DesmopJiyllum. It may be divided into sections, which are not of 

 sub generic value however : — 



1. Corallum flabelliform, subpedicellate, and becoming free. 

 Wall nearly smooth on the two faces, and with small crests on 

 the sides. 



2. Eaces of the wall with crests as well as the sides. 



3. Wall with smooth faces, but with stout spines on the sides 

 of the corallum. 



4. Wall smooth, neither crests nor spines. 



