I o4 2 
verse disposilis, et ctim annulo scrobiculorum minutorum 9-10 cirea verrucam unum- 
quemque ; a vertice visæ subellipticæ, polis Irancalis, ad angulum umimquemque spina 
subulala leviter curvata paullo divergente, lateribus convexis, verrucis rotundalis binis 
ad medium utrobique, sérié subirregulariter disposita spinarum 4 inlra marginem late- 
ralem unumquemque ; membrana délicate punctulata. 
Long, sine spin. 73 a., c. spin. 92 y ; lat. sine spin. 60 y., c. spin. 85 y. ; lat. isthm. 
21 y. ; crass. !\2 y. (PI. XXII, fig. 40 - 
Cundinainarca : Laguna de Ubaque, Easlern Andes; altit. 2066 m. N° 23 . 
In tliis species lliere are seven pairs of spines on eacli semicell, one pair al each of 
the latéral and apical angles, one pair in lhe middle of (lie apex, and one pair in the 
middle of each upper latéral margin. 
The general oulline of the cell resembles tlial of X . cintilopaeum (Bréb.) Kütz. , from 
which X. Mctyori differs in lhe three additional pairs of spines and in the presence of 
the binate central verrucæ. 
249. Arthrodesmus Incus (Bréb.) Hass. forma minor W. and G. S. West. — 
Antioquia : n os 1 and 2. 
2 50. Arthrodesmus controversus W. and G. S. West. — Antioquia : n» 8. 
25 r. Arthrodesmus convergens Ehrenb. — Antioquia: n° 5 . 
2Ô2. Arthrodesmus bifidus Bréb. — Antioquia: n° 5 . 
253 . Staurastrum antioquiense spec. nov. 
S. minutissimum, circiter lam longum cjuam latum (cum processibus), profunde 
conslrictum, sinu valde aperto ad extremum acuminato; semicellulæ transverse ellipticæ, 
polis in processus brevissimos submamillatos bispinatos horizontalité! - dispositos productis, 
ad apicem convexum processibus brevissimis submamillatis bispinulatis 3 præditæ; a ver- 
tice visæ sexangulares, lateribus concavis, angulis rotundato-mamillatis et bispinalis, inlra 
sed juxla margines processibus brevissimis bispinulatis 3 ; membrana tenuissima et glabra. 
Long, sine proc. i 3,5 y., c. proc. 17,5 y.; lat. (c. proc.) 16-17,5 y. ; lat. isthm. 5,3 y. 
(PI. XXI, fig. 29). 
Antioquia : Laguna above Medellin, Central Andes; altit. 23 oo m. N os 1 and 2. 
This minute Staurastrum resembles in its front view sonie of the smaller forms of 
St. furcatum Eiirenb., but is much less. The vertical view is al once distinctive, since 
il is 6-angular, with six equal mamillate processes in lhe lower wliorl and only three 
apical ones, one of lhe latter occurring just within each alternate concave side. 
254 . Staurastrum arcuatum Nordst. 
Forma semicellulis robustioribus, angulis crassioribus ; isthmo laliori. Long, sine 
spin. 28 y. ; lat. c. spin. 46 y- ; lat. isthm. 12 y. — Antioquia : nos 1 and 2. 
255 . Staurastrum brachiatum Ralfs. — Antioquia : n" s 1 and 2. 
256 . Staurastrum brevispinum Bréb. var. inerme Wille. 
Long. 66-74 y- ; lat. 54 - 60 y. ; lat. isthm. i 4 -i 5 y. 
Cundinamarca : n° 24 (frequent). 
