. Bulletin of the British Museum (Natural History). Zoology . CARDIGAN BAY RECENT FORAMINIFERA 195 distinctly and densely perforate; aperture countersunk, a short, curved slit, oblique to the basal suture, joining it at the junction with the basal suture of the previous chamber, bearing a flat tooth on the proximal side. Dimensions. Maximum diameter 0-13 mm, height o-6 mm. Material. Twelve specimens only, most of them with the last chamber broken. Variation. Specimens occur with four pairs of chambers visible and up to 0-22 mm in diameter. Depository. () Slide 1970 : 11 :
. Bulletin of the British Museum (Natural History). Zoology . CARDIGAN BAY RECENT FORAMINIFERA 195 distinctly and densely perforate; aperture countersunk, a short, curved slit, oblique to the basal suture, joining it at the junction with the basal suture of the previous chamber, bearing a flat tooth on the proximal side. Dimensions. Maximum diameter 0-13 mm, height o-6 mm. Material. Twelve specimens only, most of them with the last chamber broken. Variation. Specimens occur with four pairs of chambers visible and up to 0-22 mm in diameter. Depository. () Slide 1970 : 11 : 26 : 393-397. Provenance. Described specimen Cardigan Bay, Brit. Mus. Core 14. Remarks. This is the only species of Cassidulina we have so far recovered in any numbers in Cardigan Bay. The specimens are extremely small (possibly juvenile) and the details of the test consequently rather difficult to make out. Although smaller, about half the size, they are very close to Cassidulina crassa var. reniforme Norvang in shape and chamber form. They differ in that the aperture appears to be oblique to the basal suture rather than developed along it as in Nor- vang's fig. h. In this regard our specimens more resemble Islandiella islandica (Norvang) but the tooth does not appear to protrude in our specimens and the wall is granular (two crushed specimens examined in polarized light). Norvang referred his new variety to Cassidulina crassa d'Orbigny but this is untenable. The original description and the later redescription of Heron-Allen & Earland (1932) from d'Orbigny's collection in Paris and additional Falkland Islands material show that C. crassa is a large species, up to 1 mm diameter with five pairs of chambers and aperture almost at right angles to the basal suture. Apparently similar forms in the northern hemisphere were distinguished as C. obtusa by William- son (1858) who, with his usual accuracy, figures the aperture as a long slit, parallel to the periphery, as in C. laevi
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