96 BRITISH FRESHWATER RHIZOPODA. 



G-enus 40. CORYTHION Taranek, 1881. 



Arcella (pars) BHEENBBEain Abh. Akad. Berlin, 1841, p. 410. 

 ? Euglypha (pars) Perty Kenntn. kleinst. Lebensf. (1852), 



p. 187. 

 Trinema (pars) Leidy Freshw. Rhiz. N. Amer. (1879), 



p. 226. 

 Gorythion Taeanek in Sifczb. bohm. Ges. Wiss. 1881, p. 232. 



Test small, hyaline, composed of small non-imbri- 

 cated, oval, silicious plates ; compressed ; in broad 

 view sub-circular to oviform ; transverse section ellip- 

 tical ; aperture sub-terminal, ventral, or oblique, 

 circular or oval; plasma colourless, granular, only 

 partially filling the test ; nucleus placed posteriorly ; 

 contractile vesicles one or two in number ; pseudo- 

 podia filose, more or less numerous, straight, radiating. 



Synopsis oe the British Species. 



Test sub-circular or ovoid; transverse section oval or 

 lenticular ; aperture ventral. (1) C. duhinm. 



Test ovoid ; transverse section oval ; aperture sub-terminal, 

 oblique. (2) G. pulchellum. 



1. Corythion dubium Taranek. 

 (Plate XLVIII, figs. 6-18.) 



Arcella constricta 



Ehbbnbbro (pars) in Abh. Akad. BerKn, 1841, i, p. 410, pi. iv, i, 

 f. 35 ; Mikrogeol. (1864), pi. xxxix, iii, f. 3. 

 Arcella disphaera 



Ehebnbbeg (pars) in Abh. Akad. Berlin, 1841, i, p. 410, pi. iv, ii, 

 f. 12. 

 Trinema acinus 

 Leidy (pars) in Freshw. Rhiz. N. Amer. (1879), pp. 226-228, pi. xxxix, 

 e. 10-13, 18. 

 Corythion dubium 

 Taeanek in Sitzb. bohm. Ges. Wiss. 1881, p. 282, f. 3 ; in Abh. bohm, 



Ges. Wiss. (6) XI (1882), pp. 31, 43-46, 65, pi. iii, &. 17-24. 

 Pbnabd in Mem. Soc. Genfeve, XXXI, i (1890), il, pp. 188-189, pi. xi, 

 fe. 18-26; in Amer. Natur. XXV (1891), pp. 1071, 1079; Fauna 

 Rhiz. Leman (1902), pp. 531-532, 5 figs. ; in Arch. Protist. II (1903), 

 p. 272 ; op. cit. IX (1909), p. 265 ; Sarcodines in Oat. Invert. Suisse 

 (1905), pp. 110-111 ; in Brit. Antarct. Exped. I (1911), pp. 220, 229, 



pp. IJ 

 .13; 



pi. xxii, I. 3 ; in Deux, exped. antai'ct. franf. (1911), pp, 4, 6 



