332 Reports and Proceedings — Geological Society of London, 



of coral reefs. Tlie material obtainetl in the great boring, the lagoon 

 borings, and lagoon dredging at Funafuti has yielded a considerable 

 quantity of Halimeda ; and Dr. Guppy has described a Halimeda 

 Limestone in the Solomon Islands. Evidence such as this shows 

 that the important deposits of calcareous plant-remains forming at 

 the present day can scarcely be paralleled by any deposit formed in 

 past geological times, except, possibly, the limestones of the Alpine 

 Trias, which owe their origin to the thallophytes Diphpora and 

 Gyroporella. Among other Halimeda Limestones mentioned by the 

 authors are those of Christmas Island, Fiji and Tonga, and the New 

 Hebrides. The examples from the last-named group are described 

 in detail. They differ considerably one from the other in the con- 

 <lition of preservation of their chief organic contents. Chemical and 

 microscopic analyses of the several examples are given. Halimeda 

 seems to be more liable to decay than Lithothamnion, corals, or fora- 

 minifera, and yet it appears to retain its structure to a considerable 

 depth in reefs. Much of the fine powdery limestone associated with 

 coral reefs, and more especially with upraised coral islands, may be 

 primarily due to lagoon and other deposits formed by the agency of 

 Halimeda. 



2, " Notes on the genera Omospira, Zophospira, and Turritoma ; 

 with descriptions of New Species." By Miss Jane Donald. (Com- 

 municated by Professor E. J. Garwood, M.A., Sec, G.S.) 



In a previous paper the author referred to the researches of Ulrich 

 and Koken among the earlier Gasteropoda, and to the groups into 

 which they had divided them. Much knowledge is still required with 

 regard to their origin and relationships before really satisfactory 

 divisions can be made. The new species described in the paper belong 

 to three genera, characterised by the possession of a band on all the 

 whorls formed by the gi-adual filling up during growth of a sinus, and 

 not a slit, in the outer lip. The genera Loplwxpira, Whitfield, and 

 Turritoma, Ulrich, are not really true MurcliisonidEe, but are allowed 

 for the present to remain in that family. Ulrich places Omospira in 

 the family Raphistomidte, but it is not a characteristic member, for 

 the whorls are more convex and the spire higher than is the case 

 with the other genera belonging to the family. Ulrich's desciiption 

 is quoted and discussed, and one new species is described from beds 

 of Upper Bala age. Of the genus Zophospira, Ulrich's four sections, 

 and sub-sections of certain of these, are discussed. Five new species 

 are referred to the perangidata section, one new species and one 

 variety to the hicinda section, and one species to the robusta section. 

 One new species is described of Turritoma. The specimens dealt 

 with are mainly from the collections of Mrs. Gray, the Sedgwick 

 Museum, the Bristol Museum, and the Geological Survey of Scotland. 



The Rev. H. H. Winwood, in exhibiting a series of water-colour 

 drawings of Mexican scenery, said that these beautiful sketches were 

 executed by Miss A. C. Breton, during a recent visit to Mexico; and, 

 as the International Geological Congress was about to meet in that 

 country, she thought that some of the Fellows might like to see 



