Genus II: ALLOSORUS, Bernhardi. 
Gex. Cuan.—Sori spuriously-indusiate, rotundate, covered by the 
revolute subherbaceous margin of the pinnules, at length confluent 
into a transverse line (parallel to the margin), often becoming 
effuse; the receptacles punctiform. Veins in the fertile fronds 
simple or forked, from a central costa; in the more divided sterile 
fronds simple or forked in the ultimate segments; venules free. 
Fronds dimorphous, dwarf, herbaceous, bi-tri-pinnate; the fertile 
contracted, i. e., with revolute siliculiform pinnules. 
Caudex short, decumbent. 
Few, if any, of the Ferns which are indigenous to Great Britain, 
have given rise to such conflicting opinions as this, as to the genus 
to which it belongs. Linneeus, and the older botanists, referred 
it to Osmunda and Onoclea; Villars to Aerostichum ; while of 
the other names which have been applied to it, all apparently 
under the impression of its being a pteroid Fern, the Allosorus of 
Bernhardi claims priority, and we adopt it with some limitations. 
Allosorus, as here restricted, is a small genus of three or four 
dwarf elegant parsley-like Ferns, widely scattered over the globe. 
Perhaps it should be united to Cryptogramma, with which it was 
doubtfully associated by the author of the latter genus, the only 
material difference between them being that A/losorus has puncti- 
form receptacles, whilst in Cryptogramma the receptacles are linear 
and oblique. In habit and aspect they are quite alike. We follow 
Mettenius and others, in keeping them distinct, on account of the 
difference in the receptacle, to which we attach considerable import- 
ance. In the typical species of Cryptogramma, the sori form short 
lines along a portion of the veins, after the gymnogrammoid type, 
and these lines being parallel, and near together, unite laterally 
as they become effused, and so form a broad linear mass transverse 
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