58 Proceedings of the Royal Physical Society. 



ment ; tliat they grew in a verticillate or umbellate manner, 

 has already been shown by Ettingshausen.^ 



It will be seen from what has been already stated, that 

 Palceoxyris is generally believed to be a seed-vessel. If, 

 then, these organisms contained seeds or spores (and there 

 is little reason to think that they were attached to its 

 external surface), unless they had been extremely minute, 

 some indication of their presence would surely have been given 

 in the compressed condition, by their imparting a granula- 

 tion to the outer surface of the fossil, but such an appearance 

 has not, as far as I am aware, ever been observed. 



I have examined a few uncompressed individuals. The 

 " segments " in all cases are concave externally, the sutures 

 being raised to form a very slight " collerette," whose presence 

 has already been pointed out by ISTathorst in other species.^ 



The chief characters of the species of the genus Palceoxyris 

 are derived from the width and number of the spiral seg- 

 ments, and the angle at which they cross the body of the 

 fossil. 



Palceoxyris has extended through a long course of time, 

 few genera having the same geological range. Brongniart 

 described Palmoxyris regularis from the " Gres bigarre " 

 (Lower Trias), and Lesquereux, Palceoxyris {Spirangium) 

 intermedium, from the sub-conglomerate of Pittston (Lower 

 Carboniferous).^ 



I still retain Brongniart's name Pala^oxyris for these fossils, 

 for although it is now clear that the plants have no affinities 

 with the recent Xyris, none of the other names that have 

 been substituted for Palceoxyris have any claim to be 

 adopted in preference to the designation originally applied 

 to these paradoxical fossils. 



Before describing the British members of Palxoxyris, it 



1 Uber Palffiobromelia, I. c. 



^ Om Spiranginm ocli dess forekomst i sk&nes Kolforande bildniugar. Kongl. 

 Yet.-Akad. Forhandl., vol. xxxvi., pp. 81-93, pis. vi., vii. Stockholm, 1879. 

 Owing to the language in which this paper is Avritten, I am sorry I cannot 

 fully avail myself of its contents, especially knowing that any paper from 

 the pen of M, Nathorst is well worth careful attention. 



^ Coal Flora of PenusyL, vol. ii., p. 521. 



