136 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
COLLEMA (Hill.) Web. in Wig. Prim. FI]. Hols. 89. 1780. 
PuateE 21, 
The thallus is foliose and, like the last, is inclined to be irregular, though on the 
whole somewhat orbicular. Taken all together, the thalli of the members of the genus 
are the most gelatinous of all lichen thalli. As in the last, also, the cortical layers are 
entirely wanting, nor is there a distinct algal layer. The alge are plainly forms of the 
genus Nostoc, and the heterocysts may usually be plainly seen. The chains of algal 
cells are quite long and variously curved, and are commonly somewhat more numerous 
toward the upper side of the thallus. The common color is bluish-olivaceous or black- 
ish. The attachment of the thallus is as in the last genus. 
The apothecia are on the whole larger than those of the last genus and are hardly so 
numerous, though found more or less frequently in all of our species. A thalloid 
exciple is commonly present and extends somewhat above the margin of the disk. 
The common color of the disk is some shade of brown, and it may be flat, concave, or 
convex. The hypothecium is pale or brownish as is also the hymenium. The para- 
physes are commonly simple, but branched ones may be found in any of the species. 
The spores are commonly pale or hyaline, though always more or less muriform when 
fully mature. ’ 
The genus is intermediate between Synechoblastus and Leptogium, but much 
closer to the former genus, with which it agrees as to thallus structure. As regards the 
spores, however, it is perhaps nearer to the latter. 
Seven forms have been reported from the State. On earth, or more rarely on rocks 
or over mosses. Found in moist places. 
Type species Collema lactuca Web. loc. cit. This is the same as Synechoblastus 
nigrescens (Huds.) Stizenb., hence Collema must in all probability replace Synecho- 
blastus, and some other name be substituted for it in its present acceptance. 
EXPLANATION OF PLATE 21.—Fig. 1,a plant showing the thallus and the apothecia. Fig. 2, a lobe of 
the thallus with apothecia. Fig. 3, a section of an apothecium; a, the hymenium; b, the hypothecium; 
¢, the inner thallus with hyph and algal filaments; d, the ventral horizontal hyph;e, the rhizoids. Fig. 
4, a section of the thallus; a, the algal filaments; b, the fungal hyphe; c, algal filaments; d, the rhizoids. 
Fig. 5, a paraphysis and an ascus. Fig. 6, free muriform spores. Fig. 7, algal filaments. Fig. 1, natural 
size; fig. 2, enlarged about 4 diameters; figs. 3, 4, enlarged 400 diameters; figs. 5-7, enlarged 650 diameters. 
From Schneider. 
KEY TO THE SPECIES. 
On rocks. 
Thallus lobes somewhat broad and short, rounded.......... 6. C. furvum. 
Thallus lobes narrower and longer. 
Apothecia sessile or subpedicellate on the somewhat 
narrowed and ascending lobes..................-.- 5. C, plicatile. 
Apothecia adnate on the narrower, often ascending 
lobes... 0.22222 cece eee ee eeee 7. C. pustulatum. 
On earth. 
Thallus rather thick (rarely on mossy rocks)...............- 1. C. pulposum. 
Thallus thinner. 
Spores usually four in each ascus..................... 4. C. limosum. 
Spores eight in each ascus. 
Apothecia numerous, not often deeply immersed.... 3. C. crispum. 
Apothecia fewer and more often deeply immersed. 2. C. tenaz. 
1. Collema pulposum (Bernh.) Ach. Lich. Univ. 632. pl. 14. f. 9. 1810. 
Lichen pulposus Bernh. Journ, Bot. Schrad. 1799!: pl. 1. f. 1. 1799. 
Thallus usually more or less orbicular, middle-sized, 15 to 80 mm, in diameter, very 
gelatinous when wet, frequently showing a rosulate arrangement of the lobes or granules; 
rather thick, the thick lobes repand-crenate and often imbricated, especially toward 
