408 Dr. J. E. Gray on the Arrangement of the Families 



2. Bryopsis. The cell slender, without any internal fibres. 



3. Chlorodesmus. (Harvey, Ner. Bor.-Am. iii. 30. t. 40 c.) 



II. Cell or plant at first simply elongate (like the true Siphonese), at length 

 developing at the apex a number of branched articulated filaments 

 formed of elongate cells. Zoospore in the cell of the branched filament. 

 Siphoneae barbatse. 



Fam. 4. Valoniaceae. 



* Stein tubular, vesicular, and branched. 



1. Valonia. 



** Stem nodulose, with whorls of jointed, byssoid, deciduous fibrilli, and 

 a head of radiating larger cells, which are also deciduous. 



2. Acetabularia. Cell of head radiating, united. (Harvey, Ner. 

 Bor.-Am. t. 42 a.) 



3. Cliftonella. Cell of head radiating, free ; stem not perforated. 

 (C. calyculus (Polyphysa Cliftonii, Harvey?).) 



4. Polyphysa. Cells of head clustered. (P.penicillus. Harvey, Ner. 

 Aust. 1. 11.) 



*** Stem annulated, covered with a tuft of forked jointed filaments, 

 f Head a tuft of slender filaments. 



5. Penicillus. Stems very slender, many interlaced together, form- 

 ing a thick stipes. (P. arbusculus, Harvey, Ner. Aust. t. 22.) 



6. Chamadoris. Stem single, separate, thick, annulate. (C. annu- 

 lata, Harvey, Ner. Bor.-Am. 42. t. 42 b.) 



■ff Head branched; branches like the stem, annulate. 



7. Apjohnia. (Harvey, Ner. Aust. t. 5.) 



fft Head a reticulated frond. 



8. Struvea. (S. macrophylla, Harvey, Ner. Aust. 1. 1. 7. S.plumosa, 

 Harvey, ib. t. 32.) 



Suborder II. Arthromorpha. 



The cells many, united together, forming a chain-like filament, 

 one at the end of the other ; sometimes in the older parts, as the 

 stems, the threads arc incorporated into a solid or tubular axis. 



A. The zoospores developed in some dilated cells, forming a 

 beaded, thread or in a large cell situated at the end of the branches 

 or branchlets. 



* The spores in beaded threads radiating from the centre, and densely 

 packed into a spherical ball immersed among the branchlets. 



Fam. 1. Batrachospermese. 

 Frond gelatinous, clothed externally with slender articulated 

 ram ul i on a solid stem of densely interwoven threads. 



