48 THE NORTH AMERICAN SLIME-MOULDS 



b. Sporangia \vithout columella. 



i. Sporangia nucleate, calcareous at center. 



* Stipe yellow . . . . 28. P. nucleatum 

 ** Stipe white . . . . 29. P. luingatense 



ii. Sporangia non-nucleate. 



* Sporangia purple ... 30. P. ne<wtoni 

 ** Sporangia blue, spotted with red 



31. P. psittacinum 

 *** Grey or white, iridescent betimes. 



Sporangia white, discoidal ; stipe yellow 



32. P. discoidale 

 Sporangia lightly calcareous, iridescent, sub- 

 globose, diam. about = to the stout, brown, 

 slightly wrinkled stipe 33. P. leucophaeum 

 °''° Sporangia globose or sub-globose. 

 X. Small, .5 mm. 



t Stipe erect, clear brown 



34. P. nodulosum 

 tt Stipe weak, yellow, stuffed 



35. P. maculatum 

 XX. Larger, lime-capped; stipe strand-like 



36. P. didermoides 

 XXX. Stipe snow-white, fragile 



37. P. leucopus 

 xxxx. Stipe generally distinctly fluted 



t Sporangia laterally compressed, 



fan-shaped 38. P. compressum 



tt Sporangia typically globose, um- 



bilicate below, connate, etc., 



strongly calcareous 



39. P. notahile 



ttt Sporangia reniform, concave 



below P. a fine, see under 38 



tttt Sporangia larger, to 1 mm., 



nearly limeless, iridescent 



40. P. tropicale 

 °''°° Sporangia obovate, compound, clustered, the 

 stipe fuscous, fluted, short. 



41. P. nicaraguense 

 **** Sporangia yellow, rarely iridescent or brown. 

 ° Capillitial nodes white. 



x. Stipe also white 



42. P. sulphureum 

 XX. Stipe flesh-colored, spores smaller 

 43. P. carneum 

 XXX. Stipe red or reddish brown 



44. P. citrinellum 



