A EEMABKABLE MARINE OEGAJSriSM. 451 



-the organism as I found it, to state what appear to rae to be the 

 only two possible explanations of its very remarkable structure, 

 •and to leave the future to decide which, if either, of these 

 explanations is correct. 



In conclusion it may be wortb while to refer for a moment 

 to tbe enigmatical fossil Stromatoporidce *, some of wbich bear a 

 marvellously close resemblance to Pontoholhos, and may quite 

 possibly have been of the same nature. 



Ohristchuroh, N. Z., 

 June 30, 1897. 



P.S. — From the report of the meeting at wbich this paper 

 was read, I see that Professor Howes found some apparent 

 vestiges of sponge-spicules in the specimen which I forwarded to 

 him for examination. I have not observed any spicules in my 

 own numerous preparations, and am quite sure that those found 

 must have been present simply as foreign bodies. I note also 

 that Mr. Gr. Murray suggested a comparison with the algal 

 pseudomorphs of sponges described by various authors, but I 

 have seen nothing in the structure of Pontoholhos to indicate 

 any connection with a sponge. 



Ohristchurch, N. Z., January 1898. 



EXPLANATION OP THE PLATES. 



Plate 26. 

 Pontoholhos manaarensis, gen. et sp. nov. 



Fig. 1. The largest specimen, side view. Natural size. 



Fig. 2. The largest specimen, vertical section. Natural size. 2^) pit- 



Fig. 3. An irregular specimen, formed apparently by union of three growing 

 side by side. Seen from above. Natural size. 



Fig. 4. A small specimen seen from above. Natural size, p, pits. 



Fig. 5. Part of a vertical section cut by hand, stained with iodine-green and 

 mounted in glycerine. Drawn under Zeiss A. Oc. 1. Showing the 

 network of darkly staining material (protoplasm ?), the successive 

 surface-layers of the same (s), and the irregular layers of calcareous 

 granules (I), s.l. the outermost layer of the specimen. 



Fig. 6. Part of a vertical section stained with iodine-green, cut by the 

 parafSn method and mounted in Canada balsam. Drawn imder 

 Zeiss D. Oc. 1. Showing the darkly staining layers and network and 

 a few sand-grains (c/). 



* For a general account of these fossils, see Nicholson and Murie, Journ. 

 Linn. Soc, Zool., vol. xiv. p. 187. 



