70 BRITISH FEESHWATER RHIZOPODA. 



ponds ; in addition to these localities certain species 

 or varieties are peculiar to the fauna of deep lakes, 

 where they have attained in most cases a considerable 

 amount of specialisation, e. g. G. avipvlla var. major in 

 its large form 184-265 ju. in length, G. trochus sp. ver., 

 G. calceolus, G. Isevis, and G. myosurus. None of these 

 deep water forms has yet been recorded from the 

 British Isles, and with the exception of Loch Ness no 

 investigations of this Rhizopod fauna have been carried 

 out ; from that lake however some empty and perhaps 

 imperfect tests were found by Penard which appa- 

 rently belong to an undescribed species of this genus. 

 The writer has elsewhere* recorded the occurrence 

 in Yorkshire of a single empty test doubtfully ascribed 

 to G. Isevis, but on further consideration has come to 

 the conclusion that it may have been an abnormal 

 form of Trinema. 



Synopsis op the British Species. 



Test circular in transverse section. 



Composed of non-imbricated discs. (1) C. ampulla. 



Composed of imbricated scales. (2) C. trochus. 



1. Cyphoderia ampulla (Ehrenberg) Leidy. 



(Plate XLV, figs. 2-6 ; Plate XL VI, figs. 1-6; and 

 figs. 139-147 in text.) 



D'ifflugia ampulla 



Eheenberg in Ber. Akad. Berlin, 1840, p. 199 j in Abh. Akad. Berlin, 



1871 (1872), pp. 234, 274, pi. iii, i, f. 11. 

 Peitohard Hist. Infus., ed. 4 (1861), p. 553. 

 Vifflugia lagena 



Eheenberg in Abh. Alfad. Berlin, 1841, i, p. 413, pi. iv, ii, f. 11 ; 



Mikr. Lebens in S. and N. Amer. (1843), pp. 72, 125, pi. iv, ii, f. 11 ; 



Microgeol. (1854), p. 198; in Abh. Akad. Berlin, 1871 (1872), pp. 



145, 235, pi. ii, b, f . 2 ; loc. cit. p. 413, pi. iv, ii, f. 11. 

 Cyphoderia margaritacea 

 ScHLTJMBEEGER in Afin. Sci. nat. (3) III (1845), pp. 254-266. 

 Peety Kenntn. kleinst. Lebensf. (1852), p. 188. 

 PEBSBNltrs in Abh. senckenb. nat. Ges. II (1858), pp. 225, pi. xii, fE. 



28-36. 

 Stein in Abh. bohm. Ges. Wiss. (5) X (1859), Ber. p. 42. 



* Wailes & Penard, in ' Froo. Roy. Irish Acad.,' vol. xxxi, pt. 65. 



