122 



ENDOSPOREAE 



[DIDYMIUM 



nearly the apex of the sporangium. Capillitiuin a network 

 of purple-brown threads spreading from all parts of the 

 columella. Spores with pale purplish-grey walls enclosing 

 yellow or colourless contents, marked with small scattered 

 warts, and several clusters of rather stronger warts, 9 to 11 \x. — 

 Comatricha caespitosa Sturgis in Bot. Gaz., xviii. 186, t. xx, 

 figs. 1 to 4 (1893) ; Macbr. N. Am. Slime-Moulds, 124. Diachaea 

 Thomasii Rex, var. ? Lister Mycetozoa, 92 (1894). 



Fig. 103. — /. sporangia; g. sporangium after dispersion of spores ; h. capillitium 

 and spores ; i. j. spores ; (Woods Holl, Mass). 



This species was placed by Dr. Sturgis in the genus Comatricha ; its 

 affinities however would seem to be rather with Diachaea on account 

 of the membranous although limeless character of the stalk and 

 columella. It is closely allied to D. cylindrica (q.v.). D. caespitosa 

 has been recorded hitherto only from the Eastern United States ; it 

 has been gathered at Kittery, Mne. by Prof. Thaxter, at Woods 

 Holl, Mass. by Mr. M. B. M. Davis, and in North Carolina {fide Prof. 

 Macbride). 



Hab. On moss.— Woods Holl, Mass. (B.M. 1324). 



Order II. — Didymiaceae. 



Deposits of lime in the form of crystals or crystalline discs 

 distributed over the sporangium- wall ; capillitium without 

 lime-knots ; sporangia simple, except in Mucilago, where they 

 are combined into an aethalium. 



KEY TO THE GENERA OF DIDYMIACEAE. 



Lime-crystals stellate ; sporangia single. (15) Didymium. 



Fig. 23. — Didymium squamulosum Fr. 

 a. Two sporangia, one entire, the other showing 



columella and capillitium. 

 times. 



Magnified 12 



b. Capillitium and fragment of sporangium- 

 wall, with crystals of calcium carbonate 

 and two spores. Magnified 200 times. 



Fig. 23. 



Lime-crystals stellate, heaped together, at first concealing 

 the confluent sporangia. (16) Mucilago. 



Fig. 24. — Mucilago spongiosa Morg. 



a. Aethalium. Natural size. 



b. Capillitium and fragment of sporangium- 



wall, with crystals of calcium carbonate 

 and two spores. Magnified 200 times. 



Fig 24. 



