Page:Quarterly Journal of the Geological Society of London, vol. 28.djvu/154

120 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 24, 5. Rotalinoe from the Antwerp Crag. Reuss*, Sitzungsb. Akad. Wiss. Wien. vol. xlii. pp. 355 et seq. 1860.

Planorbulina farcta (type).

Conical Planorbulina kalembergensis (D'O.). Pl. tenuimargo (Rss. pl. l. f. ll).

Plano-convex. Truncatulina varians, Rss. (Pl. 2. fig. 12). Thick Tr. lobatula, or, rather, Pl. Ungeriana, subvar.

PULVINULINA REPANDA (type).

"Auricula" group. Pulvinulina Brongniartii (D' 0.).

Rotalia Beccarii (type).

Rotalia Parkinsoniana (D' 0.). R. orbicularis, D'O.

These types and subtypes are comprised also in the foregoing list of the Rotalines from the English Crag.

§ XI. Conclusion. — With reference to the Cretaceous Foraminifera, generally speaking, and as far as our observations lead us, we may say that, excepting Discobina Binkhorsti (Rss.), of the Maestricht Chalk, there is no Discorbina known in this great series of formations ; indeed that species seems to be the oldest of its genus. Of the other Rotalinae, there are numerous deep-sea forms of Rotalia, Pulvinulina, and Planorbulina. A rare Calcarina in our White Chalk, many in that of Maestricht, numerous Orbitolinoe (Tinoporus and Patellina) in some of the Cretaceous formations, and crowds of Orbitoides in some Chalk-strata of France and elsewhere, complete the Cretaceous Rotaline group.

With the closely allied Globigerinoe, on the one hand, and the Nodosarinoe (including Cristellaria &c.) on the other, the Rhizopodist has to deal largely when examining the Cretaceous rocks. In the former case, individuals, innumerable and variable, predominate, increasing in number upwards with the successive formations from the Neocomian to the Gault, Chalk-marl, and Chalk, in England. In the latter case the variations of all degrees and value become almost as numerous as the individuals ; and these abound far more plentifully than the Rotalines. Such of the latter as we have more especially had to treat of in this memoir (namely, Planorbulina, Pulvinulina, and Rotalia) are more equally distributed all through this series of deposits. Taking them in succession, we find that the typical Planorbulina is represented in all the columns of our Table. The subtype Pl. Haidingerii, taken as the leading form of the helicoid or conical Cretaceous forms, is represented in all the columns except 7, 10, 16, 18, and 21. The Nautiloid varieties, typified by Pl. ammonoides, occur in all except No. 14. The plano-convex or Truncatuline varieties, grouping around Truncatulina lobatula, fail only in Nos. 5, 11, 18, and 21. In all these cases the absence is probably not real ; further search may supply such forms.

The Pulvinulina type of Rotalinae is also well represented in these Cretaceous deposits, as shown by our columns. Only No. 21


 * See also Bullet. Acad. Roy. Sc. Belg. vol. xv. p. 154; and further on, p. 127.