180 Geological Society. 



the cell, which bladiler is annoilwith three spines set in one whorl. 

 In MiUrpora the sjtines are nnusiially long and set at right angles 

 to the thread. This kind of thread-cell alone occurs in the ten- 

 tacles ; it occurs also more sparingly in the hydrophyton. 



The other kind of thread-cell is larger and ovoidal in form, 

 closelv resembling that figured by Allman as occurring in Gctiimaria 

 imple.va. These thread-cells are confined to the hydrophyton. 

 They form densely set zones around the bases of the zooids. 



The other species of MiUepora examined ap])ear to agree in all 

 essential particulars with that occurring at Tahiti. They have 

 mouthed and monthless zooids, but these are nor arranged in regu- 

 lar svstems. They have the same two kinds of thread-cells, with 

 a similar distribution. The Tahitian Milleporn, like the others 

 examined, is infested by a parasitic fungus, which exists in the 

 soft superlicial tissues, as well as in the substance of the corallum, 

 and has a decided green tint. 



GEOLOGICAL SOCIETYT. 



March 22, 187G.— Professor P. Martin Duncan, M.B., F.R.S., 

 President, in the Chair. 



" On the Triassic Strata which are exposed in the Cliff' Sec- 

 tions near Sidmouth, and a note on the occurrence of an Ossife- 

 rous Zone containing Bones of a Lahi/rinthodon." By H. J. 

 Johnston Lavis, Esq., F.G.S. 



The author described the base of the cliffs east of Sidmouth as 

 composed of the Marl w^hich is the uppermost subdivision of the 

 Trias in South Devon, capped in Littlecomb Hill and Dunscomb 

 Hill by Greensand and Chalk, and in Salcombe Hill by Greensand 

 alone. In the vallej- of the Sid it is largely exposed at the surface. 

 Close to the mouth of the Sid the Upper Sandstone crops out 

 beneath the marl, forming a cliff overhanging the river. To the 

 west of Sidmouth there is a low projecting cliif, the Chit rock, 

 formed also of the Upper Sandstone ; and at the western end of this 

 is a fault which has given the Chit rock an upthrow of at least 

 40 and perhaps of 80 feet, since it has no marl capping it, and in 

 its lithological character it resembles the middle part of the Upper 

 Sandstone. To this point the dip is to the east ; but westward of 

 the fault the dip is at first to the west for about half a mile, when 

 the sandstone reappears with an easterly dip, having formed a 

 synchnal curve. It is overlain by Marl and Greensand in Peake and 

 High-Peakc Hills, which are capped with Chalk gravels. West of 

 High-Peake Hill the Sandstone forms the whole cliff. The author 

 described the general characters i)rcsented by the Triassic beds in 

 the section under notice, and mentioned the occurrence at about 

 10 feet from the top of the Sandstone of a peculiar series of beds, 

 composed of coarse sandstone, containing scattered nodules of marl 

 from the size of a pea to that of a hen's egg, together with numerous 



