70 BIUTISH FRESHWATER 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. C. ampulla var. major in 

 its large form 1 84-265 /u, in length, G. troclms sp. ver., 

 C. calceolus, G. lasvis, 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 un described species of this genus. 

 The writer has elsewhere* recorded the occurrence 

 in Yorkshire of a single empty test doubtfully ascribed 

 to C. Ixvis, but on further consideration has come to 

 the conclusion that it may have been an abnormal 

 form of Trinema. 



SYNOPSIS OF 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 XLVI, figs. 1-6; and 

 figs. 139-147 in text.) 



Difflugia ampulla 



EHRENBERG in Ber. Akad. Berlin, 1840, p. 199 ; in Abh. Akad. Berlin, 



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

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

 Difflugia lagena 



EHRENBERG in Abh. Akad. Berlin. 1841, i, p. 413, pi. iv, n, f. 11 ; 



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

 Cyphoderia margaritacea 



SCHLTJMBERGER in Ann. Sci. nat. (3) III (1845), pp. 254-256. 

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

 FRESENITTS in Abh. senckenb. nat. Ges. II (1858), pp. 225, pi. xii, ff. 



28-36. 

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



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



