. The British freshwater Rhizopoda and Heliozoa. tly in size. West (in Soc., ZooL, vol. xxviii) records individuals fromAthry Lough, W. Ireland, measuring 450 ^ withoutthe spines. The transparent chitinous test sometimesexhibits a cancellated or punctated surfacing. SomeTerrington Oarr examples were found by the sameauthor to be of a pale yellow colour and minutelyscrobiculate. The scrobiculations were irregularlydisposed, being scattered more or less in groups,and between them were numerous much smallerpunctulations. CENTEOPYXIS ACDLEATA. 135 Var. spinosa var. nov. (Plate XVI, fig
. The British freshwater Rhizopoda and Heliozoa. tly in size. West (in Soc., ZooL, vol. xxviii) records individuals fromAthry Lough, W. Ireland, measuring 450 ^ withoutthe spines. The transparent chitinous test sometimesexhibits a cancellated or punctated surfacing. SomeTerrington Oarr examples were found by the sameauthor to be of a pale yellow colour and minutelyscrobiculate. The scrobiculations were irregularlydisposed, being scattered more or less in groups,and between them were numerous much smallerpunctulations. CENTEOPYXIS ACDLEATA. 135 Var. spinosa var. nov. (Plate XVI, fig. 15, and fig. 26 in text.) Test purely chitinoiis, without adherent sand-grains,semi-transparent; yellowish brown when young, turn-ing to a darker brown with age (like Arcella vulgaris),and often partially or wholly covered with diatom-frustules. The mouth lobate or of unequal outline,variable in width, the margin sometimes slightly in-verted. Spines variable in number and also in length,of the same substance as the test, and Pia. 26.—Centropyxis aculeata var. spinosa. a, a -well-developed form ;b, an example showing variation; c, lateral view of this form (inoutline). Prom Dunham Marsh, Cheshire, x 260. Dimensions: Diameter in face view 120-140/a;greatest width in side view 30-40 jx. In Sphagnum; frequent in Cheshire and North Wales. This variety seems to have been regarded by mostobservers as indistinguishable from the type. Weare, however, of opinion that the structure of the test,its more numerous spines, and particularly the lobate 186 BRITISH ITEESHWATEE EHIZOPODA. mouth, are characters which justify the separation ofthis form under a varietal name. In our experience itmost frequently occurs in wet Sphagnum. The varietyis further distinguished from the type by its beingmore compressed and altogether more delicate inappearance. With regard to G. aculeata and its varieties, it mustbe confessed there is not a little ambig\iity. Formsare met with, chiefl
Size: 1470px × 1700px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauth, bookcentury1900, bookdecade1900, bookidcu31924000623961
