﻿288 



DR. STANLEY SMITH ON AUL1NA li O TIFOE31LS, [vol. lxxii,. 



mature eorallite the septa assume a radial symmetry, although 

 the bilateral symmetry of its early growth-stages is sometimes 

 traceable in the adult state through the presence of a cardinal 

 septum shorter than the rest, and is indicated in some species 

 by a prolonged counter-septum. Both the major and the minor 

 septa dilate at the theca, and the latter terminate there ; but the 

 major septa, in an attenuated form, advance into the intrathecal 

 region, and frequently dilate again at their axial edge. The central 

 part of the eorallite is occupied solely by the tabulae. 



Confluence and dilatation of septa are characters comparatively 

 rare in the Uugosa, but of very frequent occurrence in the 

 Aporosa. 



Genotype : Phillipsastrcea (Astrcea) Jiennahi (Lonsdale). 

 Type-specimen of Ph. Jiennahi : No. 6185, Museum of Practical 

 Geology. 



The type is possibly the holotype, but is much more probably 

 one of two. syntypes. Edwards & Haime assumed the latter to 

 be the case, and chose it as the lectotj'pe. 



Description of Type- Specimen of Pkillipsastrcea htnnuhi 

 (Lonsdale). (PI. XXII, figs. 1-4.) 



No. 6185 & Sections 28348-28349, Museum of Practical Geology (' Daniel 

 Sharpe Collection ' — part of the ' Geological Society Collection '), For 

 literature and history, see p. 284. 



The specimen is a weathered and rounded block measuring 

 some 10 cm. along its greatest length and about 4 cm. through 

 its thickest part. There are two jjlane polished surfaces, transverse 

 and longitudinal respectively to the direction of growth. The 

 material is translucent and of a grey colour, except near the 

 surface, where it is bleached and opaque. Superficially, it is 

 iron-stained. Weathering has reacted more vigorously upon the 

 coral tissue than upon the interstitial calcite. and so has engraved 

 the coral structures into the stone. The calcite occupying the 

 interseptal spaces stands out from the surface, and counterfeits 

 actual septa, while that filling up the intrathecal region projects as 

 a central prominence. 



Kxternal Characters. 

 None present. 



Internal Characters. (PL XXII, figs. 2-4.) 



Transverse section. — Epitheca almost but not entirely 

 absent, weak traces being detectable here and there. Confluence 

 on the part of the septa is not highly developed : the septa may 

 be confluent ; but, for the greater part, those of one eorallite abut 

 against those of another, or intermingle in a confused network. 

 The thecaa are of uniform size, measuring 3 mm. in diameter ; 



