332 Mr. J. Ralfs on the Nostochinese. 



Sporangia oblong, three times longer than broad, much broader 

 than the ordinary cells, one or two on each side of the vesicular 

 cell, the outer ones generally smallest. 



The best distinctive mark of this species is the subacute extre- 

 mities, combined with the short filament and littoral habitat. 

 There are rarely more than one or two groups of enlarged cells ; 

 when only one is present it is situated near the centre of the 

 filament. I believe that the attenuated extremities are constant, 

 at least in the young plant, unless the filament has been broken. 



The var. (3. differs in having much slenderer filaments : I am 

 not sufiiciently acquainted with it to determine whether it be, as 

 Mr. Thwaites supposes, a distinct species. 



Plate VIII. fig. 7- «, ^, ordinary form ; c, var. ^. 



2. S. Jacohi (Ag.). Filaments elongated, their ends usually attenu- 

 ated ; ordinary cells subspherical ; vesicular cells spherical ; spo- 

 rangia oblong or cylindrical. SphcBrozyga Jacohi, Agardh, Icones 

 Algarum Europsearum ! ; Berkeley in Eng. 13ot. t. 2826. fig. 2. 



Upper Mill, Dolgelley ; near Swansea, /. 11. Durham Down uear 

 Bristol, Mr. Thwaites ! 



Carlsbad, Agardh ! Madeira, Rev. T. Salwey. 



Sphcerozyga Jacohi occurs in thick bluish green gelatinous 

 masses, from which the filaments issue in long rays. The fila- 

 ments are moniliform, elongated, and generally taper at their 

 ends. Ordinary joints at first somewhat quadrate but finally 

 orbicular, the terminal one longer than broad and usually coni- 

 cal. Vesicular cells spherical, larger than the ordinary joints, 

 but not so broad as the sporangia. Sporangia oblong or cylin- 

 drical, one or two on each side of the vesicular cell. 



Agardh's figure represents his Spharozi/ga Jacohi as having 

 the ordinary joints closely united, in fact separated merely by 

 transverse dissepiments, and consequently so unlike the present 

 plant, that I should scarcely have suspected their identity if 

 Mr. Borrer had not afforded me an opportunity of examining an 

 authentic Carlsbad specimen which he received from Agardh 

 himself. 



Spharozyga Jacohi in some respects agrees with S. Carmichaelii; 

 but the filaments are stouter and more elongated, the ordinary 

 cells are more orbicular, its habitat is also different, and the dried 

 jdant wants the opake verdigris appearance so usual in the latter. 

 The orbicular ordinary and vesicular cells distinguish it from 

 S. elastica and /S'. lej)tosperTna. 



Plate VIII. fig. 8. a, immature filament; h, matiue state. 



3. S. elastica (Ag.). Filaments monihform, dissepiments conspi- 

 cuous ; ordinary cells quadrate ; vesicular ones elliptic ; sporangia 



