282 



POPULAR HISTORY OF LICHENS. 



more gelatinous Collemas. Its spores are ellipsoid, acumi- 

 nate at the ends, having a delicate wall, and containing 

 several transverse rows of cellules separated by indistinct 

 and sometimes unsymmetrical septa. 



3. Collema corniculatum (corniculum, a little horn), 

 which resembles the preceding, but has convolute, bifid or 

 trifid lacinia3, obtuse, with entire margins, is of peculiar in- 

 terest as possessing, according to Tulasne, an angiocarpous 

 fructification. Its apothecia he describes as small tubercles, 

 perforated, at the apex, grouped in large numbers. The 

 thecse and paraphyses are arranged as in fflidocarpon, and 

 the spores are ovoid and acuminate at the ends. Its sper- 

 mogones are difficult of detection; they occur as minute, 

 grouped punctuations towards the extremities of the thalline 

 lacinise, while the apothecia occupy the opposite ends or base. 

 Under the microscope they appear like little transparent pe- 

 rithecia nestling under the epidermic or cortical layer of the 

 thallus. The spermatia are linear, straight, and very minute. 

 (E.B. 1635.) 



4. Collema rupestre. Thallus lobate, plicate- undulate, 

 macro- or micro-phylline, blackish-green ; the lobes entire 

 or crenate. Apothecia scutellate, flattish, scattered, dark 

 brown. The lobes are decumbent or ascending, often im- 



