Geological Society. 435 



Ceratoccenia elongata, g. & sp. n. ; ScypJiocoenia siaminifera and e.v- 

 ceha, g, & sp. n. ; Batliycoenia hemisphcerica, sp. n, ; Cotivexasti'cea 

 Waltoni,^. & H. ; Cryptocoenia oheliscas, Mich.; C. plana, sp. n. ; 

 C. Riyauxi, sp. n. ; C. microphylla, Tomes; Stylina, s'p.; Montli- 

 valtia caryophyllata, Lamx. ; M. Riyauxi, sp. n. ; Cladophyllia 

 Babeana, E. & H. ; Septastrcea riyida, sp. n. ; Confusastrcea Uiyaaxi, 

 sj). n. ; C. maynifica, Tomes ; Confusastrcea, sp. ; Isastrcea limi- 

 tata, Lamx. ; /. explanata, Goldf. ; /. tuberosa, sp. n. ; Latimceaadra, 

 sp.; L. lotharivga, From.; T hamnastrcva mammosa, E. & H. ; 

 Anahacia complanata, Defr. ; A. Bouchardi, E. ik H. ; Genabacia 

 stellifera, E. & H. ; and Microaolena excelsa, E. & H. From the Coral 

 E.ag : Stylina, 2 s-p.: Calamop)hyllia jJseudostylina, Mich. ; Rhabdo- 

 jjhylUa Fhillipsi, E. & II. ; Thecosmilia atmularis, E. & H. ; Con- 

 fusastrcea, sp. ; Bhnorphophyllia jureiisis, Beck. ; Latimceandia 

 sequana, From. ; Isastnva explanata, Goldf. ; /. heliantJwtdes, 

 Goldf. ; /. portlandica, From. ; TrocJioseris oolitica, sp. n. ; Thamna- 

 stra^a ? latima^androidea, sp. n. ; T.'? concinna, Goldf. ; T. foUacea, 

 Quenst. ; T. yibbosa, Beck. ; Microsolena exjxmsa, Etall. ; and 

 Comoseris irradians, E. «& H. 



7. " On the Structure and Affinities of the family Eeceptaculi- 

 tidae, including therein the genera Ischadites, Murch. ( = Tetmyonis, 

 Eichw.), Splioirosponyla., Pengelly, Acantlioclionia, g. n., and Recep- 

 taculites, Defr." By Dr. G. J. Hinde, F.G.S. 



The author's observations have been derived from the study of 

 numerous examples of the family from Silurian and Devonian strata 

 in Devonshire, the west of England, Belgium, Silesia, Bohemia, the 

 isle of Gotland, Canada, and the United States. In an historical 

 sketch the author showed that the members of this group have been 

 at various times referred to pine-cones, Foraminifera, sponges, corals, 

 cystideans, and tunicate Mollusca, and that the latest authorities 

 who have written on them consider their systematic position as 

 altogether doubtful. 



The present mineral constitution of these fossils is either of crys- 

 talline calcite, silica in a secondary condition, iron peroxide, or iron 

 pyrites, or they occur as empty moulds, and from the similarity to the 

 present mineral condition of undoubted siliceous sponges, the author 

 thinks that the Beceptaculitidae were also originally siliceous. The 

 skeleton of the members of the group consists of modified hexacti- 

 nellid spicules, in which the summit-ray of the spicule is changed 

 iuto a rhomboidal or hexagonal plate with the four horizontal rays 

 or arms immediately beneath it, whilst the vertical ray or shaft 

 tapers to a point, and terminates freely in Ischadites and Acantlio- 

 clionia ; in Sphcerosponyia it is partially absorbed -, and in Recepta- 

 culites it develops a plate at its distal extremity. The sjiicular rays 

 are traversed by axial canals, as in other hexactinellid spicules, and 

 these unite in the central point of junction of the rays. The spi- 

 cules are definitely arranged so that their summit-plates form regu- 

 larly oblique rows crossing each other, and the horizontal rays 

 radiating and transverse rows. 



