Geological Society of London. 281 



actual descriptions of the following kinds of Polyzoa and Forami- 

 nifera, with notes on their relations, etc. It included : — 



Polyzoa. 



Stnmatripora graciUs. TVlilne-Edw. 

 Idmonea dorsata, Hagenow. 

 Entalophora raripora, D'Orb. 



Jessonii, sp. nov. 



striatopora, sp. nov. 



■ gigantopora, sp. nov. 



Lichenopora, sp. 



? pauciporn, Vine. 



IJroDiopora stellata, Goldfuss. 



poly taxis, Hagenow. 



Osculipora plebeia, Novall. 

 IVuncatula, sp. 



Membranipora cantabrigiensis, sp. nov. 

 Microporella, sp. (? aniiquata.) 

 Lunnlaria cretacea, Defr. & D'Orb. 



Diustopora cretacea, Vine. 



var. lineata, var. nov. 



■ — fecunda, sp. nov. 



megalopora, sp. nov. 



FORAMINIFERA. 



TFebbina l(evis,So\\-dS. I Trochammina irregularis?, D'Orb. 

 tuberctclata, Sollas. j Textularia, sp. 



in.— April 29, 1885.— Prof. T. G. Bomiey, D.Sc, LL.D., F.R.S., 

 President, in the Chair.^The following communications were read : 



1. "On the Structure of the Ambulacra of some Fossil Genera 

 and Species of Regular Echinoidea." By Prof. P. Martin Duncan, 

 M.B. (Lond.), F.E.S., V.P. Linn. Soc, F.G.S. 



After noticing the general knowledge which exists about the 

 structure of the ambulacra in the Cidaridae and the elaborate investi- 

 gations of Loven on the Triplechinidse, the author brought before 

 the Society the results of his own work with and without the co- 

 operation of his fellow-worker in the description of the Echinoidea 

 of Sind, Mr. Percy Sladen, F.G.S. , and which referred to the Diade- 

 matidge and the Arbaciadge of the recent faunas. Starting with the 

 knowledge of the construction of the modei'n Diadematidee, the 

 author investigated the genera Hemipedina, PseAidodiadema, Pedina, 

 Hemicidaris, Diplopodia, and Cyphosoma. The necessity for the 

 re-establishment of the genus Diplopodia was shown, and a new 

 genus, Flesiodiadema, was founded. Pseudodiadema, shorn of the 

 tbrms included in these genera, remains and differs more from 

 Diadema than has been believed. The method of the growth of the 

 great plates of Hemicidaris was explained, and the comparison 

 between the peristomial plates of some of the Diadematid^ and the 

 imiversal structure of the ambulacral plates in Pedina was made. 

 The author considered that there are six types of ambulacra in the 

 regular Echinoidea, so far as the group has been investigated, there 

 still remaining much to be done. These types are the Cidaroid, 

 Diadematoid, Arbacioid, Echinoid, Cyphosomoid, and Diplopodous. 

 In con;lusion the succession in time of the structures which charac- 

 terize these types was considered. 



2. "The Glacial Period in Australia." By R. von Lendenfeld, 

 Ph.D. Communicated by W. T. Blanford, LL.D., F.R.S., Sec. G.S. 



Although several previous writers have suggested that boulders 

 and gravels found in different parts of Australia are of glacial origin, 

 the evidence is vague and no clear proof of glaciation has been 

 brought forward. During a recent ascent of the highest ranges in 

 Australia, parts of the Australian Alps, the author succeeded in 



