320 MR. G. S. WEST ON SOME BRITISH 
22. Dirruueia corona, Wallich,in Ann. Mag. Nat. Hist. 
1864, xiii. t. xv. ff. 19, 20; Leidy, Freshw. Rhiz. N. Amer. 1879, 
p- 117, t. xvii. 
A rare species which I have only observed from Llyn Llydaw, 
Snowdon, and in pools, Y Foel Fras, N. Wales. In all the 
specimens observed the spines were very robust. Length of 
shell 150-160 1; breadth (including spines) 165-182 ; breadth 
of mouth 75 p. 
23. DirFLUGIA GLOBULOSA, Dujardin, in Ann. Sci. Nat. 1837, 
vill. p. 311, t. ix. f. 1 a,b; Letdy, l. c. p. 96, t. xv. ff. 25-31; 
t. xvi. ff. 1-24. D. globularis, Wallich,in Ann. Mag. Nat. Hist. 
xiii. 1864, p. 241, t. xvi. ff. 1, 2,17, 27. D. acropodia, Hertwig 
& Lesser, in Archiv fiir mikr. Anat. 1874, x. Suppl. p. 107, 
elie elOs 
A general and widely distributed species, exhibiting con- 
siderable variation in size and form. I have obtained it at 
2700 ft. on Glyder Fawr, and at 8000 ft. on Snowdon, N. 
Wales. 
The smallest forms observed were from Roundhay Park, 
W. Yorkshire. The shells were straw-coloured and slightly 
asperulate; diam. 13°5-17 4; diam. of mouth 57. (Pl. 29. 
figs. 17, 18.) 
Another small form, which was abundant from Lough Guitane 
and Tore Mt., S.W. Ireland, possessed a yellow, chitinous shell 
with an exceptionally wide mouth. Diam. 38 w; diam. of mouth 
29-33 p. 
Two specimens were observed conjugating from Cocket Moss, 
near Giggleswick, W. Yorkshire. From this locality the animals 
possessed a perfectly globose, colourless chitinous shell, attached 
to which were a few sand-grains and numerous large Diatoms. 
The mouth was relatively very small. Diam. 190; diam. of 
mouth 52 p. 
24. Dirrivueta Loposroma, Leidy, im Proc. Acad. Nat. Sei. 
Philad. 1874, p. 79; 1877, p. 307; Freshw. Ehiz. N. Amer. 
1879, p. 112, t. xv. ff. 1-24, t. xvi. ff.. 25-29.—D. crenulata, 
Leidy, 1874. 
Somewhat scarce. Diameter of shell 49-285 p. 
Form with a three-lobed mouth observed from Carlton Bank, 
N. Yorkshire ; Llyn Cwlyd and Capel Curig, N. Wales. 
