Affinities of the Palaeozoic Seeds of the Cono stoma Group . 39 
concerned in the reception and storage of pollen. Briefly stated, these 
mechanisms were as follows : — 
1. The unjoined but approximated lobes of the integument surrounded 
and overtopped a relatively large lagenostome which bore an orifice seated 
on a low central papilla. At the time of pollination it is probable that 
these lobes collectively formed a tube or funnel narrowing towards the 
mouth of the lagenostome. If so, this type possessed a functional micropyle 
which played its part in the passage of the pollen (Text-fig. 13, Physo - 
stoma). This type may be termed a fimbriated micropyle. 
2. A relatively massive canopy of united segments was perforated by 
a long micropyle which led down to a small, included lagenostome, the 
Text-fig. 12. Diagrams to show the relations of lagenostome, plinth, and canopy in Lageno- 
stoma , Pkysostoma , and Conostoma. The regions where soft-filling tissue occurs are dotted, i. e. 
the central cone of the lagenostome in Lagenostoma , a shallow cushion resting on the flanks of the 
intrusive apex of the megaspore chamber in Physostoma, and a lens-shaped cushion below the lageno- 
stome in Conostoma. Two stages of Lagenostoma are shown. 
cavity of which became confluent with that of the plinth below by delique- 
scence of the filling tissues. The pollen-grains which traversed the micropyle 
and lagenostome were received into the plinth cavity, where they doubtless 
underwent maturation. This type is marked by a plinth of considerable 
vertical extension, an organ not conspicuously developed in type 1 
(Text-fig. 12, Conostoma). 
3. The lobes of the integument were fused into a compact canopy 
which closely invested the conical lagenostome, the orifice of which 
reached to the outer surface of the seed. In this type the lagenostome 
must have been directly pollinated without the intervention of the micropyle. 
A plinth was present, but had only a trifling vertical extension (Text-fig. 12, 
Lagenostoma). 
So far as efficiency in the collection of pollen-grains was concerned, 
each type appears to have been perfectly satisfactory. The presence of 
much pollen in the lagenostome of Lagenostoma , and especially in the 
