Affinities of the Palaeozoic Seeds of the Conostoma Group. 37 
locally ; (5) a terminal, specialized, more or less pear-shaped receptacle for 
the pollen known as the lagenostome. 
These three series of types, with provisional diagnoses, are as follows : — 
i. The Physostomeae. 
Free parts of the ribbed integument consisting of separate segments 
surrounding and overlapping the large, globose lagenostome which opened 
by a small orifice inserted on the apex of a low papilla. Plinth rudimentary. 
The apex of the megaspore cavity projected into the floor of the lageno- 
stome. Ribbing at base obsolete. 
Phy so stoma elegaiis , Will. 
Physostoma Kidstonii , Arber. 
ii. The Conostomeae. 
Seeds ribbed or angled, tapering at apex : free part of integument 
consisting of more or less fused lobes. The lining of the integument formed 
the passage for the large pollen-grains and was thus a true functional micro- 
pyle leading down to the very small, included lagenostome, the wall of 
which consisted of cells with reticulated or scalariform sculpturings ; base of 
lagenostome communicating with the extensive plinth cavity into which the 
pollen-grains penetrated. Integument with a mucilaginous epidermis 
extensively developed at the apex. 
Conostoma, Williamson. 
Cylindrical or slightly flattened seeds with tapering insertion. Ribbed 
throughout, or at base with angles passing into ribs. Lobing at apex 
variable ; vascular bundles equalling or fewer than the ribs or angles ; loculi 
of canopy nearly obliterated and equalling the vascular bundles in number ; 
epidermis mucilaginous. 
Lagenostome very small, included ; cells of wall sculptured. 
Plinth conspicuous, dome shaped, with internal tissue ; well-marked 
4 tent-pole ’ and tapetum present. 
1. Conostoma oblonguni, Will. 
Organization of the Fossil Plants of the Coal Measures, Pt. viii. Phil 
Trans., 1877, p. 243, Figs. 80, 80* (PI. XI), 80* (PI. XII), 81 and 86. 
Localities. Oldham ; Dulesgate ; Shore, Littleborough ; Halifax ; 
Deighton, Yorks. 
Horizon. Lower Coal Measures. 
Seed six-angled, winged at base only ; six vascular strands ; apex 
ending in six soft, free lobes. 
Dimensions: length 6 mm., broadest diameter 2-3 mm. 
