basalibus rectangularibus et leviler rolundatis, lateribus subparallelis et subrectis (levis- 
sime convexis), angulis apicalibus late rolundatis, apice leviter emarginato-reluso in raedio ; 
a latere visæ oblongæ, lateribus parallelis, apice late rotundato ; a vertice visæ ellipticæ ; 
membrana punctata. Pyrenoide singulo. 
Long. 37-39 p. ; lat . i 5 -i 6 p.;lat. isthm. 7-8 p. ; crass. 1 1-1 r ,5 p.. (PI. XXII, fig. 48 - 49 ). 
Antioquia : Bog near the Laguna above Medellin, Central Andes ; altit. 23 oo m. 
No 5 . 
Tins small species occurred in abundance and exhibited very constant characters. It 
is a close ally of C. decedens (Reinsch) Ragib. and ils var. sinuosum (Lund.) Racib., 
from which it is primarily distinguished by the subparallel (and slightly convex) sides of 
the semicells and the broadly rounded apical angles. It is also proportionately longer 
and the apices of the semicells are retuse in the middle only (not widely retuse as in ail 
forms of C. decedens). Moreover, both side and vertical views are quite different, espe- 
cially the latter, in which there is no trace of the submamillate pôles so characteristic of 
C. decedens. 
C. propinquum should also be compared with C. subquadratum, Nordst., from 
which it differs in its smaller size, its proportionately greater length, its wider isthmus, 
the emarginate-retuse apices of the semicells, and in the form of the side view. 
224. Cosmarium pseudamœnum Wille. — Antioquia : n os 3 , 4 (abundant and 5 . 
22b. Cosmarium pseudexiguum Racib. ; W. and G. S. West., Monogr. Brit. Desm. 
III, 1908, p. 65 , T. 70, f. 25 , 26. 
Forma brevior. Forma cellulis brevioribus, celeris ut in forma typica. Long. 22 p.; 
lat. i 5 p. ; lat. isthm. 3 p . 
Cundinamarca : n° 24. 
As in other forms of this species the isthmus was exceedingly narrow. C. pseudexi- 
guum appears to be one of the most deeply constricled species of the genus. 
226. Cosmarium pseudoconnatum Nordst. — Antioquia : n° 5 . 
227. Cosmarium pseudonitidulum Nordst. — Antioquia : n° 5 . 
228. Cosmarium pseudoprotuberans Kirchn. forma. Long. 32 p. ; lat. 27-28 ; lat. 
isthm. 8 p. ; crass. 19 p.. 
Cundinamarca : n° 23 . 
229. Cosmarium pseudopyramidatum Lund. — Antioquia : n° 5 . 
23 0. Cosmarium pyramidatum Bréb. — Antioquia: n os 1 , 2 4 and 5 . Cundina- 
marca : n° 24. 
23 1. Cosmarium Quadrum Lund. — Cundinamarca : n° 23 . 
This species occurred in great abundance. AU the specimens were rather small, but 
not quite small enough to be placed under var. minus Nordst. 
Long. §7-64 p- ; lat. 48-53 p. ; lat. isthm. 18-20 p. ; crass. 26-27 p. 
232 . Cosmarium Regnellii Wille. — Cundinamarca : n° 23 . 
233 . Cosmarium Regnesi Reinsch. — Antioquia: n os 1, 2 and 5 . 
