376 Salmi .—( 9 /z Branching of the Zygopteridean Leaf. 
in the latter. Since then, however, I have had an opportunity of dis¬ 
cussing the paper with Dr. D. H. Scott, F.R.S.. I am indeed very thankful 
to him for his able criticism, and for drawing my attention to the question 
of priority in nomenclature, which I had not fully considered. The much 
older genus Clepsydropsis (Unger, 1856) should stand,^and the more recent 
genus Ankyropteris (P. Bertrand, 1909) should be merged in Clepsydropsis . 
The name Ankyropteris was first employed by Stenzel in 1889 ( 17 ) for one 
of his sections of Corda’s genus Zygopteris (1845). 
The diagnosis of the genus Clepsydropsis as now extended would be as 
follows : 
Stem with or without ‘ axillary branches or more or less equally 
forked. Catiline stele , with a solid outer xylem and a stellate ‘ mixed 
"1 
Permian 
Dineuroideae 
t Zygop 
in , 
Clepsydroideae 
teris Asteroch 
laena 
Upper 
Carboniferous 
Staur 
Oh 
S 3 
opteris 
§ Ankyro] 
jteris 
Lower 
Carboniferous 
( Culm ) 
fj 
Metaclepsy 
? Gyropl 
Diploh 
1 
Dinen 
dropsis 
reris 
1 -- 
iron 
Upper Devonian 
\ 
x X 
1 
Fig. 3. Table showing inter-relations of the genera of Zygopterideae. 
Modified from P. Bertrand (1912). 
pith 5 or internal xylem. Leaf-traces in § phyllotaxis, nipped off as closed 
rings, and distally becoming clepsydroid. Pinna-traces arising as closed 
rings and branching laterally at the base to supply similar traces to 
aphlebiae. Roots diarch. Known range : Upper Devonian to Upper 
Carboniferous (inclusive). 
The known species of the genus naturally fall into two sections : 
1. § Clepsydropsis proper.—Peripheral loops extended in the right- 
left plane (C. antiqua , Unger ; C. kirgisica , Stenzel; and Mrs. Osborn’s 
fossil). 
2. § Ankyropteris .—Peripheral loops extended antero-posteriorly (in¬ 
cluding all the species hitherto recognized under the genus Ankyropteris , 
P. Bertrand). 
