106 BRITISH FRESHWATER RHIZOPODA. 



Genus 12. HYALODISCUS Hertwig & Lesser, 1874. 



Amiba (pars) DUJAEDIN Infus. (1841), p. 235. 



Hyalodiscus HERTWIG & LESSER in Arch. f. mikr. Anat. 



X (1874), Suppl. p. 49. 

 Placopus F. E. SCHULZE in Arch. f. mikr. Anat. XI (1875), 



p. 348. 

 Vampyrella (pars) KLEIN in Bot. Centralbl. VIII (1881), 



p. 321. 



Body discoid, of indefinite outline, surrounded by a 

 band of clear ectoplasm of varying width, with a 

 reddish, frequently much vacuolated granular endo- 

 plasm in which may be detected, under favourable 

 conditions, an inconspicuous nucleus. Endoplasm 

 similar in appearance to that of Vampyrella, sometimes 

 projected into conical or filamentous processes. 



The band of transparent ectoplasm, completely 

 enveloping the body, is distinctive of this genus, and 

 separates it from the allied Vampyrellse. 



1 . Hyalodiscus rubicundus Hertwig & Lesser. 

 (Plate XIII, figs. 2-11.) 



Hyalodiscus rubicundus HERTWIG & LESSER in Arch. f. mikr. 

 Anat. X (1874), Suppl. p. 49, t. ii, f. 5; ALLMAN in 

 Journ. Linn. Soc., Zool. XIII (1877), p. 267, f. 2 > ARCHER 

 in Q. J. Micr. Sci. XVII, ii.s. (1877), p. 342, t. xxi, f. 16 ; 

 MAGGI iu Kend. E. 1st. Lomb. (2) X (1877), p. 321 ; in 

 Atti Soc. Ital. XXI (1878), pp. 313, 317 ; and in Boll. 

 Scieiit. I, an. 2 (1880), p. 34; HITCHCOCK Synops. Freshw. 

 Rhiz. (1881), p. 10; LANESSAN Traite Zool., Prot. (1882), 

 p. 48; BLOCHMANN Mikr. Thiervv. Siisswass. (1886), p. 10, 

 t. i, f. 5; SACCHI in Boll. Scient. Ill, an. 10 (1888) p. 43, 

 and loc. cit. an. 11 (1889), p. b'8 ; LEVANDER in Acta Soc. 

 Fauna Fenn. XII (1894), no. 2, p. 11, and in Zool. Anzeig. 

 XVII (1894), p. 209 ; PENARD Faune Rhiz. Leinan (1902), 

 p. 159, ff. 



Plakopus niber F. E. SCHULZE in Arch. f. mikr. Anat. XI 

 (1875), p. 348, t. xix, ff. 9-16; ALLMAN in Journ. Linn. 

 Soc., Zool. XIII (1877), p. 270, f. 4; ARCHER in Q. J. 

 Micr. Sci. XVII, n.s. (1877), p. 349, t. xxi, f. 23; 

 LANESSAN Traite Zool., Prot. (1882), p. 49. 



