i o 1 8 
Tins Alga formed small tufts consisting of from seven to twelve filaments attached 
(o the leaves and stems of aquatic macrophytes. The filaments are rallier rigid and 
fairly straight, although gently un- 
dulated from base to apex, and the 
base of each filament is a little 
decumbent. 
It stands nearest to M . robusta 
Setchell and Gardner (Algæ of 
N. W. America, Univ. Calif. Publ. 
Bot. iqo3, p. iç)4), from which it 
differs in the smaller tufts of shorler 
and narrower filaments, which are 
wider at the base than at the apex. 
Moreover, so far as could be obser- 
ved even the sheaths of the oldest 
filaments were not lamellose. 
M. crassa might also be compa- 
red with M. calotrichoides Hansg., 
a species in which the filaments are 
much more densely aggregated and 
the trichomes considerably narrower. 
The latter are also altenuated at 
the apices and sometimes pdliferous, a character which at once distinguishes it from 
M. crassa. 
Fig. 1. — Microchæte crassa sp. nov. 
a, tuft of filaments, X 40 ; b, bases of three filaments, X 500 ; 
c, apex of filament, X 500. 
Family Scytonemaceæ. 
30. Tolypothrix lanata Wartmann. — Cundinamarca : n° 23. 
31. Scytonema crispum (Ag.) Bornet. — Cundinamarca: n° 20. 
'Family Stigonemaceæ. 
32. Hapalosiphon hibernicus W. and G. S. West. — Antioquia : n° 4. Cundina- 
marca : n° 24 . 
33. Hapalosiphon intricatus W. and G. S. West. — Cundinamarca : n° 24 . 
34- Stigonema ocellatum (Dillw.) Thuret. — Cundinamarca : n° 24 . 
