Vol. 57.] THE EH^TIC PLAXT XAIADITA. 307 



23. Fossils in the Oxford Uniyeksity Museum, Y: On the Structuke 

 and Aeei:s^ities of the Ehjetic Plant Naiadita. By Miss 

 iGERifA B. J. Sollas, B.Sc. (Lond.), Xewnham College, Cam- 

 bridge. (Communicated by Prof. AY. J. Sollas, D.Sc, LL.D., 

 P.R.S., F.G.S. Eead February 6th, l&Ol.) 



[Plate XIII.] 



The Rhaetic plant-remains known as Naiadita are found in a 

 narrow area stretching down that part of the Severn Yalley which 

 lies below the Avon. Phillips ^ mentions their occurrence at Pylle 

 Hill, Bristol, and associated with Estheria at Garden Cliff, Westbury- 

 on-Severn, and Wainlode Cliff, Tewkesbury. The exact horizon of 

 these plant-beds is that which Edward AYilson named Bed K. 



The vertical thickness of rock, through which the plants are 

 distributed in layers of extreme tenuity, is 7 inches at Tewkesbury 

 and 9 inches at Westbury-on-Severn. 



These fossils are well-known, from the description published 

 fifty-one years ago by James Buckman"; but the first discoverer 

 was P. B. Brodie,^ who chose for them the name Kaiadita because 

 Lindley considered them to be monocotyledonous plants resembling 

 the members of the order Naiadaceae. Mr. J. Starkie Gardner ^ 

 re-examined them, and jDointed out that the markings supposed by 

 Lindley to have been left by the rectangular venation of a Naias- 

 like leaf, were in reality fossilized cell-walls. Mr. Gardner concluded 

 that the plant was a moss and was probably closely allied to the genus 

 Fontincdis. He spoke of a capsule, but of this he gave no 

 description. 



A slab from the Naiadita-hed of PylJe Hill, Bristol, was recently 

 sent by Mr. W. H. Wickes of that city to my father for exami- 

 nation,^ because it contains bodies which were thought to be 

 possibly gemmules of a sponge. On this proving not to be the case, 

 the specimen was handed over to me. I have since had the ad- 

 vantage of studying additional material, owing to the kindness of 

 Mr. A. C. Seward and Mr. Wickes. 



The plant, which was delicate, slender, and moss-like in habit, is 

 preserved in a more or less fragmentary condition. The state of 

 preservation varies, however, in the different strata. Some of the 

 strata contain loose leaves and disconnected pieces of stem only, 

 while in others the stems may branch, the leaves are still attached 

 to the stem, and sporangia are present also, at least occasional^ 

 attached. The sporangia are situated at the bases of leaves which 

 embrace them ; but whether they are terminal, or are borne laterally 

 on the stems, is somewhat difficult to decide. It is a point which 



1 ' Geology of Oxford ' 1871, pp. 102-105. 



2 Quart. Journ. Geol. Soc. toI. vi (1850) p. 415. 



3 ' Fossil Insects' 1845, pp. 92-93. 

 * Geol. Mag. 1886, pp. 203, 495. 



5 Proc. Bristol Nat. Soc. vol. ix (1901) pp. 100, 102. 



