46 



BRITISH FRESH WATER RHIZOPODA. 



of tlie test (fig. 129ft 1 ). In length they vary greatly but 

 are usually of about the same length on the same test. 



Although in a few localities, such as the moors of 

 the North Riding of Yorkshire and the swamps of 

 New Jersey, U.S.A., living individuals are fairly 

 numerous, none were observed in process of division 

 or conjugation. 



In the United States a variety is found in which 

 the spines are acicular and scattered over the whole 

 surface of the test. 



FIG. 130. Test of Placocista spinosa, with abnormally distended aperture, 

 x 270. From Llyn Llydaw, Snowdon. (G. 8. West.) 



The aperture is sometimes found widely distended 

 (fig. 130a), in side view showing as a notch with 

 convex sides (fig. 130&), but this probably only occurs 

 permanently in empty tests, the living animal usually 

 keeping it closed. 



2. Placocista jurassica Penard. 

 (Plate XL, figs. 7-9; and PL XLII, fig. 1.) 



Placocysia jurassica 



PENARD in Rev. Suisse Zool. XIII (1905), pp. 611-612, pi. xiv, E. 29, 



30 ; op. cit. XIV (1906), p. 136 ; Sarcodines in Cat. Invert. Suisse 



(1905), pp. 105-106 ; in Brit. Antarct. Exped. I (1911), pp. 220, 250. 

 EVANS in Proc. B. Phys. Soc. Edinb. XVII (1907), p. 11, table 1. 

 HEINIS in Arch. Hydrobiol. V (1910), p. 109. 

 BROWN in Jrn. Linn. Soc., Zool. XXXII (1911), p. 83, pi. ix, ff. 16- 



18 ; in Ann. Scott. Nat. Hist. 1911, p. 229 ; in Scott. Natur. 1912, 



pp. 109, 112. 



WAILES in Naturalist, 1913, p. 148. 

 Placocista jurassica 



SCHOUTEDEN in Ann. Biol. lacustre, I (1906), pp. 368, 369. 



