130 
THE SEAWEEDS 
Order NEMALIONINAE. 
CONSPECTUS OF THE FAMILIES. 
Helm inthocla diac e ae . 
Gonimoblast consisting of a crowded convex bunch of articulated branch- 
ing threads, free or held together by gelatine, the terminal cells transformed 
into spores. The gonimoblast external to or immersed in the thallus, lacking 
a pericarpial covering, sometimes accompanied with protective filaments. 
Sporangia mostly monosporous, sometimes triangularly divided. 
Ghaetangiaceae. 
Gonimoblast consisting of a crowded convex or umbellately expanded 
bunch of articulated threads, the terminal cells transformed into spores. 
Gonimoblast immersed in the thallus, provided with a solid pericarp. 
Sporangia cruciately or triangularly divided. 
GeUdiaceae. 
Gonimoblast consisting of a cluster of widespread branching threads, 
often becoming confluent with quasi-auxiliary cells of the thallus. The 
apices of the fertile branches confluent in a hymenium, from which the 
spores arise. Sporangia cruciately, zonately, or triangularly divided. 
Family HELM1N1 HOCLADIACEAE (Harvey) Schmitz. 
Frond filiform, terete, variously branching, mostly gelatinous, slippery. 
Structure eminently filamentous with a central axis and radiating cortical 
threads. 
CONSPECTUS OF THE GENERA. 
a. Carpogonia terminal on the younger branches of 
the cortical threads 
b. Branches of the carpogonia in the joints of the 
cortical threads : — 
(1) Threads of the medullary stratum lax . . 
(2) Threads of the medullary stratum dense 
and firmly compacted 
(3) Threads of the medullary stratum com- 
bined in a dense fasciculus. Cortical 
threads slippery. Plants more or less 
encrusted with carbonate of lime .... 
N emotion 
Targioni TozzettL 
TIelminthocladia 
J. Agardh. 
Helminthora 
J. Agardh. 
Liagora 
Lamouroux. 
