MILIOLIDA. 13 



varieties, not far removed from the transitional forms above alluded to ; the ridged marginal 

 border being almost the only character connecting it with Q. Ferussacii. 



It is very difficult, therefore, if not impossible, to define the limits of this variety, which 

 passes into the true Q. seminidum on one hand, and into several varieties (of little value) on 

 the other. The synonyms above given are merely a selection. 



Stout-ribbed Quinqueloculina are not uncommon wherever the other MiliolcB exist, 

 though they seldom occur in any great abundance ; we find their shells also in fossiliferous 

 Tertiary strata in the neighbourhoods of Paris and in the Vienna Basin. In the Crag we 

 only note its occurrence at Sutton. 



6. QuiNQUELOCDLiNA PULCHELLA, D' Orbiffny. Plate IV, fig. 3. 



QuiNQUELOCULiNA PULCHELL.4, D'Orb., 1826. Ann. Sc. Nat., vol. vii, p. 303, No. 42 ; 

 Soldani, Testae, ac. Zooph., vol. iv, p. 53, pi. 18, 

 figs, c and/". 



— Verneuiliana, Schreibersii, Josephiana, Id., 1846. For. Foss. 



Vien., p. 296, pi. 19, figs. 19—27. 



— PULCHELLA, Brady, 1864. Trans. Linn. Soc, vol. xxiv, p. 466, pi. 48, 



fig. 4. 



Characters. — Sliell traversed by several stout parallel longitudinal costae. Segmen 

 arranged as in the other Quinqueloculina. Colour white, dirty-white, or brownish. 

 Length, ^.th inch. 



The varying conditions of the surface of the shell in respect to texture and orna- 

 mentation are among the least of the secondary characters on which the artificial sub- 

 division of the Milioline groups may be founded. These characters cannot boast any 

 greater permanency than we have ascribed to those on which the larger divisions have 

 been determined. The texture of the normally porcellanous Foraminiferal shells may, 

 under altered circumstances, present every gradation from white and smooth to brown, 

 rough, and purely arenaceous ; and the surface-markings, which so many species exhibit, 

 are seen in every degree of intensity, from dehcate hair-like striae and fine riblets, 

 to deep sulcations and bar-like ribs. But, whilst it is impossible to draw any defined limit 

 between these different forms of ornamentation, they are sufficiently striking in their 

 external development to yield a ready means of dividing what would otherwise be a some- 

 what unwieldy and heterogeneous collection of forms. 



The bold and strongly ribbed Quinqueloculina pulchella is not a common shell ; and 

 only a single specimen has occurred to us in our examination of the Poraminifera of the 

 Crag. This specimen, from Sutton, is in Mr. Searles Wood's collection ; and although it 

 is broken and much worn, we have no hesitation in assigning it to this sub-species. On 

 the British coast, §. pulchella is a very rare form ; but it is more frequent in the Mediter- 

 ranean, and in tropical seas. It is occasionally found in the Tertiary fossiliferous deposits, 

 but does not appear before the Grignon Beds of the Paris Basin. 



