36 



BEITISH FEESHWATER RHIZOPODA. 



figures with any known species of Difflugia. The 

 D. glohulosa of modern authors is well known as having 

 a globose or hemispherical test, with an oral aperture 

 ■ — -comparatively large — situated not at the extremity 

 of an ovoid body, but on the basal surface (in this 

 case the ventral surface) of the hemisphere — a quite 

 different arrangement. But if we cannot accept D. 

 glob'idosa Duj. on account of its ambiguity, still less is 

 it permissible to perpetuate a name which the author 

 clearly never designed for the organism which now 

 bears it. 



A • way out of the difficulty is suggested by a 

 reference to Dr. "Wallich's paper on " Structural 

 Variation among the Difflugian Rhizopods," in the 



Fig. 51.— Difflugia globulosa Dujardin :? — D. lobostoma. After Dujardin, 

 in Ann. Sci. Nat., 2, VII (1837), t. ix, ff. 1 a, 1 6. x about 200. 



' Annals and Magazine of Natural History ' for 1864. 

 The species we have hitherto known as D. globulosa 

 Duj. is there referred to, and figured, as " Difflugia 

 globularis Duj." — obviously an error, which the writer 

 has repeated throughout his paper. There was no 

 "D. glohularin" known when Wallich, apparently 

 imconscious of his error, invented the name and 

 credited it to Dujardin. 



[It is not however necessary to take advantage of 

 Wallich's error, for the species was described, though 

 not very fully, by Ehrenberg in 1848 and figured by 

 him in 1856. His description is : " Arcella ? globulus, 

 lorica subglobosa laxe venosa-reticulata, venulis granu- 

 latis, apertura ampla simplici. Diameter -f-g'".'' The 



