cornuvia] arcyriaceae 231 



The type of Hemiarcyria pusitta Speg. (in Ann. Soc. Cient. Argent., 

 xii. 257 (1881) ), from the Argentine Republic, is not met with in the 

 quoted collections ; it is described as being an exceedingly minute 

 species, with nearly sessile, gregarious, rose-coloured and elliptical 

 sporangia, - 4 to 0"5 mm. high, - 15 to - 25 mm. diam. ; capillitium 

 forming a rather dense network of threads, 3 to 4 /a thick, marked 

 with three or four spiral bands and furnished with minute spinules ; 

 spores smooth, 7 to 9 [x diam. The species occurred on bark, and 

 does not appear to have been found more than once. 



Genus 42.— CORNUVIA Rostafinski Versuch, 15 (1873). 

 Sporangia sessile ; capillitium a network of threads with 

 thickenings in the form of simple rings ; spores reticulated. 



1. C. Serpula Rost. Versuch, 15 (1873). Plasmodium 

 creamy- white. Sporangia sessile, subglobose, about 03 mm. 

 diam. or forming curved, branched or net-like plasmodio- 

 carps, sliming, golden-yellow ; sporangium- wall membranous, 

 delicate, smooth, pale yellow. Capillitium a network of 

 freely branching yellow threads, 3 to 5 ll diam., marked with 

 well-defined prominent ring-shaped thickenings, arranged at 

 intervals of about 2 ii. or irregularly scattered ; junctions of 

 the branches without thickenings. Spores yellow, reticulated 

 with narrow bands forming a net with from eight to twelve 

 meshes to the hemisphere, 10 to 12 /a diam. ; border 05 to 

 1 fx broad. — Rost. Mon., p. 289 ; Coon in Journ. R. Micr. Soc, 

 1907, 142, tt. x, xi. Arcyria Serpula Wigand in Pringsh. 

 Jahrb. Bot., iii. 44 (1863). Ophiotheca Serpula Mass. Mon., 135. 



PI. 170. — d. sporangia ; e. capillitium and spores with fragment, of sporangium- 

 wall ; (Germany). 



This minute species frequents tan heaps. The first British gathering 

 was made in the spring of 1906 by Mr. J. M. Coon who found the 

 shining mature sporangia in abundance on bark in a tanyard at Gram- 

 pound near St. Austell, Cornwall ; he also observed the young 

 sporangia developing from cream-white plasmodium. 



Hob. On tanning bark.— Cornwall (B.M. 2029); Germany (B.M. 784). 



Order II. — Arcyriaceae. 



Sporangia simple, stalked or sessile ; capillitium a network 

 of tubular threads branching at wide angles, and thickened 

 With spines, warts, cog-like prominences or half rings (rings 

 in Arcyria annulifera), usually., abundant (sometimes scanty 

 and of free threads in Perichaena corticalis). 



KEY TO THE GENERA OF ARCYRIACEAE. 



A. Capillitium elastic : — 



Sporangia stalked ; sporangium- wall evanescent above, 

 persistent as a cup below. (43) Arcyria. 



p2 



