.^. NOTES AND COMMENTS. 325 



at approximately the same period in Jamaica, while in the heart of 

 the West Indian area radiolarian beds identical in character with 

 those of Barbados have been found. Similarly, at the last meeting of 

 the Geological Society, a paper by R. J. L. Guppy was read, 

 describing the stratigraphical relations of a similar set of beds in 

 Trinidad, and an appendix by Gregory describing the microscopic 

 structure of the rocks shows that there again we have true oceanic 

 ■deposits. This conclusion was strongly supported by Dr. Hinde, who 

 had made a careful examination of the rocks. Geologists may, 

 therefore, now fairly claim to have answered the challenge to 

 produce deep-sea oozes as part of the raised land masses. 



Another Continental Oceanic Deposit. 



The last number of the zoological series of the Linnean Society's 

 Journal is devoted to a description of the sponge remains from the 

 Oamaru deposits in New Zealand, by Dr. G. J. Hinde and Mr. W. 

 M. Holmes. The diatoms of this locality have long been known to 

 microscopists, and have been described in a series of papers by 

 Messrs. Grove and Sturt, published by the Quekett Club. The 

 interest of this deposit is due largely to the fact that it appears to be 

 a truly deep-sea pelagic deposit, and thus forms an additional illustra- 

 tion of the alternation of pelagic and continental conditions. The 

 authors remark (p. 179): "The absence of coarse arenaceous 

 materials is the same in the Oamaru as in the recent deep-sea ooze. 

 We may therefore conclude that this Oamaru rock was a deep-sea 

 deposit, formed at some considerable distance from land, and that it 

 may rightly be compared with the Diatom ooze which now forms a 

 belt of varying width surrounding the South Polar Regions, and 

 extending from the Antarctic Circle to about lat. 40° S." The 

 average depth of this diatom ooze is 1,477 fathoms, but the authors 

 think the Oamaru deposit was formerly in deeper water than this, 

 as radiolaria are so abundant in it ; they think that its closest 

 analogue is some ooze dredged by H.M.S. " Egeria," between 2,479 

 and 3,000 fathoms, off the south-west coast of Australia. The 

 sponges described belong to no species and 43 genera, and this, of 

 course, excludes those of which the flesh spicules have not been 

 found. The species are nearly all extinct, and the deposit is probably 

 to be regarded as of Upper Eocene or Oligocene age. Species of the 

 group Monactinellida preponderate, whereas in the Mesozoic sponge 

 beds this is almost unrepresented : this the authors regard as 

 another instance of the imperfection of the geological record, the 

 smaller monactinellid spicules having been rendered unrecognisable 

 during the processes of fossilisation. In the course of such a careful 

 examination of so large a series of specimens and species as that in 

 the present memoir, numerous anomalies of distribution have been 

 noticed : thus, genera known only living in the Central Atlantic 



