1895.] 



Study of Madreporarian Types of Corals. 



15 



that the so-called " Randplatte " (which the author translates as " edge- 

 zone ") is supported in the living polyp, and the author takes it that 

 the typical edge-zone has mesenteries and mesenterial loculi simply 

 because it was originally an inherent part of the polyp. It is clear 

 that such costate parts in Astraeid colonies have an entirely different 

 evolutionary history from the ccenenchyme in the Pocilloporidae, &c, 

 where no edge -zone surrounds the polyp. The author traces back 

 this difference in recent colonial types to a difference already well- 

 marked in Silurian Madreporaria — viz., the difference between the 

 calyces of a typical Cyathophyllid and a typical Zaphrentid respec- 

 tively. In the former a broad calycinal outer zone with dissepi- 

 mental base surrounds an inner tabulate area ; in the latter there 

 is no such outer zone or the very slightest indication of it. 



The author found that the families of Edward and Haime's classi- 

 fication must undergo considerable changes ; she limits herself here 

 to one or two of the most important changes suggested by her on the 

 basis of microscopic septal structure and generally of the morphology 

 of the skeleton. The family of Astraeidae E. H. hitherto included 

 two main subfamilies, the Astraeinae and Eusmilinae. The former 

 is made by the author the sole representative of Astraeidae, while the 

 latter is entirely broken up. The genera Trochosmilia, Placosmilia, 

 and their allies are referred to the family of Turbinolidae ; the genera 

 Rhipidogyra, Pectinia, Dendrogyra, Euphyllia, and a large number 

 of fossil genera are placed in a new family Amphiastraeidae erected 

 by the author. The Mesozoic representatives of this new family 

 are proved to be direct colony -building descendants of Palaeozoic 

 Zaphrentids, while the Turbinolidae are looked upon as simple corals 

 descended from the same Palaeozoic family. The Stylina group of 

 Eusmilinae E. H. are placed in the neighbourhood of the Astraeidae 

 and Amphiastraeidae as an intermediate family Stylinidae. Gralaxea 

 is regarded as a near ally of the Stylinidae ; in spite of its somewhat 

 aberrant features the author ranks it provisionally within this, 

 family. 



Edwards and Haime's group of Madreporaria Perforata is also- 

 broken up by the author. The Eupsammidae show undoubted affinity 

 with the Eungidae, and both these families, together with the 

 Astraeidae and Stylinidae, are shown to have derived their structural 

 features from leading Palaeozoic types belonging to the family of 

 Cyathophyllidae. In all of them the septum reaches a high degree 

 of differentiation in its trabecular structure, on lines already intro- 

 duced in various of the more advanced Palaeozoic tvpes. The 

 Madreporidoe (Turbinarinae E. H. and Madreporinae E. H.) are placed 

 in the neighbourhood of Pocilloporidae and Oculinidae : their simple 

 septal stracture agrees with the primitive types of septum presented 

 by Palaeozoic Zaphrentids and their allies. The Poritidae, although 



