DesTnulieee.'] infusohial animalcules. 'iSl 



lower margin inflated at the middle, very concave ; ends rounded ; 

 vesicles large, in a single row ; fillets several ; suture absent. It 

 may always be distinguished bj' the inflation at the middle of its 

 lower margin ; its single row of vesicles separates it from C. Ehren- 

 hergii. Length l-75th to l-60th, 



Closterhim Jenncri. — Small, crescent-shaped, generally sUghtly 

 constricted at the suture; when empty, colouiiess; ra^ndly tapering; 

 ends very obtuse ; vesicles in a single series. Length l-281th. 



C. Leibleinii. — Smooth, crescent-shaped ; extremities much attenu- 

 ated and sub-acute at the apex ; lower margin slightly inflated at the 

 middle ; vesicles in a single row, large. 



Var. (J.) — More slender, the central inflation less evident ; empty 

 frond of a deeper colour, and its central suture distinct. Length 

 l-291th. to l-165th. (P. 13. f. 1. and 5.) 



C. Biauce (Ehi*.) — Smooth, slender, crescent-shaped ; extremities 

 tapering ; apex sub-acute ; lower margin not inflated ; vesicles in a 

 single series. The empty frond of a pale straw colour, Avith a central 

 transverse sutui-e. It is less curved than preceding. Length 

 1-1 43rd. 



Iff Frond nearly straight, scarcely attenuated- ; ends truncate ; 

 longitudinal stria none or indistinct. 



C. didymoticum. — I^early straight, broadly linear; extremity 

 slightly tapering ; ends truncate ; reddish ; fillets obscure. 



Var. («.) — Empty frond divided by three transverse lines or 

 sutures. Rare. 



Var. (i.) Baillyanum. — Smaller, with a sutm'e only at the middle. 



C. didymoticum may be kno-wn from all the preceding species, by 

 its straight unstriated frond, combined -with truncate ends. Length 

 of var. {h.) l-65th. 



f t t t Empty frond distinctly striated, mostly coloured. 



C. attenuatum (Ehr.) — Cmwcd, attenuated ; suddenly contracted 

 at the end into a conical point ; empty frond reddish, faintly striated. 

 Kather larger than C. striolatum. The sudden contraction of its 

 extremities is characteristic. Length l-57th. 



C. costatum. — Stout, semilunate, tapering from the middle ; ends 

 obtuse ; strife few and conspicuous ; suture solitary. Fillets obscure j 

 vesicles in a single row. Empty frond reddish. Length l-75th. 



u 



