PERICIIjENA.] ARCYRIACEJE. 195 



Mass., Mon., p. 138. Physarum congestum Somm., Fl. Lap., p. 241 

 (1825). Lachnobolus congesta Berk. &: Br., in Ann. Mag. Nat. Hist., 

 Ser. 4, xvii., p. 140 ; Cooke, Myx. Brit., p. 74. Arcyria Hariotii 

 Mass., Mon., p. 155. Lachnobolus Sauteri Host., in Fuckel, 

 Symb. Myc. Nachtr., p. 76. 



Plate LXX., B. a. sporangia, x 20 ; b. capillitium with portion of 

 sporangium- wall and spores, x 600 (England). 



The type specimen of Arcyria Hariotii Mass., in Paris Herb., is 

 typical L. circinans. 



Hal}. On dead wood. Haypit, Stafford (L:B.M.162) ; Somerset 

 (B. M. 291) ; France (Paris Herb.) : Tyrol (Strassb. Herb.) ; Iowa 

 (B. M. 1027, 1028). 



SPECIES NOT MET WITH IN THE QUOTED COLLECTIONS. 



2. L. Arcyrella Rost., Mon., p. 431 (1875). Sporangia 

 pyriform, fulvons or almost straw-coloured ; stalk about as long 

 as the sporangium, yellowish ; capillitium not elastically expand- 

 ing, forming a lax irregular network, threads 2 - 5 to 8*3 //, diam., 

 attached at many points to the sporangium-wall, some threads 

 descending into the tube of the stem, marked with numerous small 

 obtuse warts ; spores smooth, 7 to 8 /x, diam. 



Hab. Jutland. 



This description applies to Arcyria albida. 



3. L. Rostafinskii Racib., in Rozpr. Mat.-Przyr. Ak. Krak., xii., 

 p. 80 (1884). Sporangia stipitate* ovoid-conical, apex rounded, 

 yellowish-grey, the lower part of the sporangium with a distinct 

 membrane, hemispherico-patelliform, the upper part destitute 

 of a membrane ; capillitium well developed, forming a net adnate 

 to the sporangium-wall by numerous attachments, the upper part 

 with many free rounded ends ; threads 4*2 to 8'2 //, diam., 

 marked with slender ridge-like processes forming a reticulation ; 

 spores smooth, yellowish, almost colourless, 7'5 to 8*3 ^ diam. 



Hob. On dead birch roots. Near Cracow, Poland. 



This description suggests a form of Arcyria flava Pers., in which 

 developments sometimes occur closely corresponding with the above 

 account. 



SPECIES EXCLUDED FROM THE GENUS. 



Z. globosus Rost. = Arcyria albida Pers. 



Genus 39. PERICHJENA Fries, Symb. Gaster., p. 11 (1817). 

 Sporangia sessile, subglobose or plasmodiocarps ; sporangium-wal 1 

 of two layers, the outer thickened with dark angular granules, 

 w y hich are exceptionally absent in the upper part, the inner 

 membranous ; capillitium of branching or simple threads, spinose, 

 minutely wartcd, or nearly smooth, marked with irregular 

 constrictions ; spores yellow, minutely warted. 



