40 



at many points. A. incarnata is similar but the capillitium ex- 

 pands more and is only lightly attached by a few threads to the 

 center of the cup. There are two other red species similar to A. 

 incarnata but nor common, and distinguished by spore and other 

 characters. A. insignis has small pinkish or flesh-colored spo- 

 rangia, arranged usually in small clusters. The common yellow 

 form is A. nutans which has a long expanding capillitium so 

 lightly attached that it is often separated when found. The 

 white or grayish cylindrical form with capillitium firmly at- 

 tached is A. cinerea. A variety of this called digitata has the 

 sporangia clustered together with the stalks confluent or partly 

 so. A. pomiformis is a small, yellowish form, globose or almost 

 so, and scattered in small developments. A. stipata is copper- 

 colored. 



Genus 21. PERICHAENA 



The genus is still controversial as to the members composing 

 it. The two common species mentioned are generally accepted. 

 P. corticalis forms chestnut-brown or purple-brown, subglobose, 

 sessile sporangia, often crowded. The dehiscence or splitting of 

 the sporangium-wall is in an irregularly horizontal manner or 

 by a distinct, convex lid, exposing the yellow spores and scanty 

 yellow capillitium, which latter may be absent entirely. The 

 capillitium may have simple or branched threads, free or at- 

 tached to the wall. The threads are irregular in breadth, warted 

 or spinose, but rarely smooth. P. depressa is similar but the 

 sporangia are larger, much flattened, and usually angled by 

 mutual pressure. The dehiscence by a lid is pronounced, and the 

 capillitium is usually abundant. In either species lime is some- 

 times present in the wall or lid, or both. 



Genus 22. CERATIOMYXA 



All species of the Mycetozoa, except C. fruticulosa the only 

 member of this genus, have spores that are developed within a 

 wall or peridium whether definite, indefinite, or evanescent. In 

 the present species the spores are developed on the outside of 

 the fruiting body. The fructification consists of numerous, small 

 white bodies called sporophores, which branch or fork and re- 

 semble a minute bush or tree. On them are many small, slender 

 stems, each of which carries an ellipsoid, colorless spore. The 



