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CHORDARIACEiE. 
IV. 
many small potatoes. This genus, lumpy as it is, is closely allied in structure to 
Mesogloia , from which it is chiefly distinguished by the shapeless frond. The frond 
in the latter group is branching, with a pinnate habit. A further advance in 
structure is made in Chordaria , where the axis becomes very compact ; and in 
Scytothamnus, a genus found at New Zealand, the frond attains its maximum of 
structure. In that group the substance is as tough and leathery as it is among the 
Fucacece , yet an appeal to the microscope shows a filamentous structure not 
essentially differing from that found in Chordaria or Mesogloia. The genera Ela- 
chista and Myrionema are a little different in structure from the other genera of 
the order, and indicate a passage into Edocarpaceae. In them some of the 
filaments composing the frond are free, or not enclosed in gelatine ; but as the 
spores are lodged among the filaments which are compacted together into the base 
of the fronds, I prefer retaining these genera in the present order. By Prof. J. 
Agardh, Elacliista is referred to Ectocarpaceae, and Myrionema retained in Chordari- 
aceie, but both are so closely allied to each other, and also to Leathesia : that I am 
unwilling to separate them. 
The spores of the Chordariaceae are very generally obovate, obtuse at the apex 
and narrowed to the base, and in many they taper so considerably as to become 
almost club-shaped. They are enclosed in pellucid perispores, and attached to some 
portion of the filamentous structure of the frond, generally to the filaments form- 
ing the periphery or outer stratum. They are usually accompanied by paranemata. 
In Balfsia alone they form prominent, wart-like son, not unlike those of Stilophora 
among Dictyotace®. The colour of the frond varies from a greenish to a brownish 
olive, and is sometimes very dark. It is not much altered in drying. 
About forty-five species of this Order have been described from various parts of 
the world. The majority are natives of the colder portion of the temperate zone, 
both north and south; and some species, such as Leathesia tuberiformis and Chordaria 
fiagelliformis , are equally common in the Northern and Southern Hemispheres. 
I have found the gelatine of Chordaria fiagelliformis , extracted by allowing the 
fronds to remain a day or two in fresh water, useful in causing small Algae, which 
are not of themselves sufficiently gelatinous, to adhere to paper. It is however too 
weak for any except very slender kinds. With this exception, none of the species 
are used in the arts. 
SYNOPSIS OF THE NORTH AMERICAN GENERA. 
* Frond cylindrical , branching. 
I. Chordaria. Axis cartilaginous, dense, solid (at length hollow in the centre) 
Filaments of the periphery unbranched. 
