LAGENIDIALES 985 



Sporangium a complex of short, irregular digitations; resting 

 spores several in a thallus, asexually formed; in Achlya 



L. destruens, p. 991 



In rotifer eggs L. oophilum, p. 992 



Thallus predominantly septate, at least when forming gametangia 

 Thallus typically forming a single sporangium, predominantly mo- 

 noecious, the gametangia arising by septation of the thallus; in 



pollen grains L. pygmaeum, p. 993 



Thallus typically forming more than one sporangium and game- 

 tangium, monoecious or dioecious; in various substrata 

 Thallus predominantly of small extent, usually occupying only one 

 cell of the substratum 

 Thallus elements more or less constricted at the cross walls, 

 somewhat cylindrical or with irregular lobations or short 

 straight or crooked branches, not forming a complex; rest- 

 ing spores sexually or apogamously formed 

 Zoospores formed exogenously; resting spores sexually 

 formed 

 In Conjugatae 



Oospore wall smooth L. rabenhorstii, p. 994 



Oospore wall bullate L. papillosum, p. 996 



In rotifers L. distylae, p. 996 



Zoospores formed endogenously, encysting prior to swarm- 

 ing; resting spore apogamous .... L. parthenosporum, p. 996 

 Thallus elements regularly or irregularly tubular, forming a 

 more or less intricate complex of irregularly branched 

 segments; resting spores apogamous 

 Segments more or less isodiametric, rarely torulose; in 



Closterium L. intermedium, p. 997 



Segments more or less irregularly contorted; in gametangia 

 and zygotes of filamentous Conjugatae 

 Segments thick, strongly contorted, with numerous short 

 branches or lobulations; discharge tube 2 [i in diam- 

 eter, often swollen beneath the wall of the host zygote ; 



resting spore dentate L. entophytum, p. 998 



Segments slender, more regularly branched; discharge tube 

 very delicate, expanded beneath the wall of the host 

 gametangium; resting spore smooth-walled L. gracile, p. 999 

 Thallus extensive, mycelial 

 In algae 

 In Blue-green Algae (Lyngbya) L. nodosum, p. 1000 



