86 SEAWEEDS 
SPOROCHNACEZ. 
General Characters—The sporangia are lateral 
branches of hairs arising from the superficial 
cells, and are unilocular. The growth of the 
thallus is trichothallic, the growing-point being 
situated in a group of cells at the base of the 
terminal tuft ofhairs. The cells are produced in rows 
free from each other, but these become united below 
into a parenchymatous tissue. A thallus of con- 
siderable size, diversity and beauty of form is 
characteristic of the group. 
The Thallus, originating as described, is mostly 
branched on all sides and round or flat in section. 
The growing branches are crowned each with a 
tuft of hairs, which falls off on the cessation of growth 
in length. The parenchymatous cells composing the 
thallus decrease in size towards the margin, and 
the more superficial ones contain the bulk of 
the chromatophores. 
The Reproductive Organs occur in sori or on definite 
fertile portions of the thallus, and the sporangia are 
lateral branches of the sporangiophores. The spor- 
angia are mostly obovate or elongate-ovate in form, 
and spring in some cases from the base of the spor- 
angiophores, more frequently at intervals through- 
out their length. In Aereia the sporangiophores 
occur in sori, and in the other genera—Sporochnus, 
Carpomitra, Bellotia, Encyothalia, and Perithalia— 
definite fertile branches of the thallus are produced, 
of more or less characteristic forms, those of Spo- 
