1 12 Oliver . — On Physosto 7 na elegans , Williamson , 
Lyginodendron . Whether Conostoma oblongum should be referred to the 
same quarter must remain in suspense till it has been more fully 
investigated. 
As to the parentage of Physostoma , we remain completely in the dark. 
It is just possible that its vegetative organs are not represented in our 
nodules. The delicacy of its vascular strands, and the readiness with which 
the tissues surrounding them gave rise to lacunae, may be significant of 
a general organization that was unable to resist decay. 
Apart from this possibility, the organization of the seed — showing as it 
does close relationship with the Lagenostoma-g roup — seems to point to 
some form with Sphenopteris-foliage as its source. This conjecture is con- 
sistent with the facts available regarding L. Kidstonii , which, of all the 
Lagenostomas, shows the closest approach to Physostoma } Whether the 
petrified remains of the Physostoma- fronds are included under the com- 
prehensive Lyginodendron oldhamium , and if so whether they are 
anatomically distinguishable, must remain for future investigation to deter- 
mine. The Systematist who handles recent plants finds the reproductive 
and vegetative organs in continuity, and thus escapes much of the perplexity 
to which the Palaeobotanist is liable. The predicament outlined above is 
perfectly comparable to that which would obtain with certain genera of 
recent Cupressineae or Umbelliferae were they only known in a fragmentary 
state. 
In conclusion, it remains to acknowledge help from many quarters. 
My thanks are due to Prof. C. E. Bertrand for the loan of the unique 
Maurice Hovalacque series, whilst Prof. Bottomley, Mr. R. Kidston, 
Dr. Scott, Mr. D. M. S. Watson, and Prof. F. E. Weiss have all placed 
preparations at my disposal. To Dr. Smith Woodward, of the Geological 
Department of the British Museum, I am indebted for facilities in examining 
the preparations of the Williamson Collection. Mrs. D. H. Scott kindly 
counted the ribs and tentacles of a number of Physostomas in the Scott 
Collection, thus swelling materially the numbers available for the curve on 
p. 84. In addition to supplying me with sections of the seed during 
a number of years, Mr. James Lomax, of Bolton, has spent much labour in 
the endeavour to trace the plant that bore these seeds. Were it not that 
good fortune is the determining factor for success in quests of this kind, 
I am confident that his patience and good judgement would have been 
rewarded long ago. Finally, I have to acknowledge grants towards the 
purchase of specimens from the Fossil Botany Committee of the British 
Association for the Advancement of Science. 
1 A resemblance not overlooked by Mr. Arber (loc. cit.). This seed, in view of the corre- 
spondence of characters, has been here assigned to the genus Physostoma (see p. 102). 
