280 THE MYXOMYCETES 



the Gulf, often on watersoaked wood or on moist soil. Also Europe, 

 North Africa. 



3. Trichia Holler emend. Rost. 

 Mon. 243. 1875. 



1768. Trichia Haller, Hist. Stirp. Helv. 3 : 114, in part. 



Sporangia distinct, sessile or stipitate; capillitium of distinct elastic 

 threads, free, acuminate at each end, yellow or more rarely reddish 

 or brown ; spores generally yellow. 



The trichias are easily recognized among their kind by their beauti- 

 ful, spirally wound, elastic capillitial threads, the elaters; these are 

 entirely free, simple or only rarely branched, and generally acute at 

 each extremity. The spiral bands, sometimes called taeniae, are gener- 

 ally very uniform in thickness, distance from each other, and pitch, 

 and in many species are further reenforced by minute longitudinal 

 plications running from one spiral to the next. Furthermore, the spirals 

 may be smooth or spinulose, the elaters uniform throughout or en- 

 larged by nodes and swellings. Taken altogether, the trichias, with the 

 species of the genus next following, exhibit the highest degree of 

 differentiation attained by the Myxomycetes. 



It is not unusual to find trichias with a more or less net-like capil- 

 litium and hemitrichias with the net broken into more or less elater- 

 like portions, suggesting the very close relationship of the two genera. 

 Hemitrichia helvetica Meylan is an example. Miss Lister regards this 

 species as an aberrant development of Trichia affinis. 



Most of the earlier authors, including Haller, used the generic name 

 Trichia to cover a variety of forms. It is here used with the limits 

 sketched by de Bary in 1859 and 1864, and followed more exactly 

 ten years later by his pupil, Rostafinski. 



KEY TO THE SPECIES OF TRICHIA 



a. Sporangia sessile b 



a. Sporangia stalked m 



b. Pulvinate or somewhat plasmodiocarpous; usually gregarious, sometimes 



crowded c 



b. Sporangiate; usually crowded, sometimes merely gregarious h 



c. Black or dark purple; spores over 13 n d 



c. Lighter; spores under 13 /x. e 



d. Wall single; elaters 7-8 ju thick, warted 5. T. cascadensis 



d. Wall double; elaters 4-6 n, smooth or spiny 4. T. alpina 



e. Dark ochraceous to purplish brown 6. T. macbridei 



e. Yellow or olivaceous; peridium membranous, little encrusted 7. T.lutescens 



e. Reddish or purplish brown / 



/. Capillitium with prominent spines 3. T. iowensis 



/. Capillitium spineless g 



