86 



THE GEOLOGIST. 



sea-shore of the south-east of England, and long thought to be recent, 

 has been referred by us to the Loudon Clay. (Annals Nat. Hist. 

 3 ser. vol. iv. p. 346.) Differences in the development of the little 

 prickles constitute the chief distinctions of the closely allied forms 

 D. spinulosa, Montagu, D. Adolpkina, D'Orb., D. spinescens, Heuss, 

 D. spinosa, D'Orb., and D. spinicosta, D'Orb., in all of which the 

 -ongitudinal riblets, so characteristic of well-grown Nodosarinse, are 

 modified as spines and prickles ; whilst in another closely allied set of 

 forms, the prickles are less regularly arranged in rows, and of varying 

 strength ; namely, in Nodosaria hirsuta, D'Orb., N, rugosa, D'Orb., N. 

 punctata, D'Orb., N. aculeata, D'Orb., N. hispida, D'Orb., N. con- 

 spurcata, Keuss, JV. aspera, D'Orb, Dsntalina aculeata, D'Orb., D. 

 floscula, D'Orb., D. scabra, Keuss, Marginulina hirsuta, D'Orb., and 

 M. cristellaroides, Czjzek. The modifications of form, from the 

 straight Nodosaria, through the bent Dentalina, to the still more 

 curved Marginulina, do not any more represent specific differences 

 than the modifications of the exogenous riblets and prickles. Nor 

 do the differences in the relative size and gibbosity of the chambers 

 afford more distinctive characters ; but all these features are subject, 

 one with another, to endless gradual transitional modifications in the 

 Nodosarinse. D. spinulosa and its subvarieties are exceedingly com- 

 mon in the London Clay and in the Septarien-Thon of Germany and 

 other Tertiary beds. 



Figs. 6 and 7. Textularia (Verneuilina) communis, D'Orb. The 

 figures do not distinctly exhibit the peculiar triangular apex of the 

 shell ; a feature arising from its being at first a triserial Textularia ( Ver- 

 neuilina), before it grows with a single line of chambers only, so taking 

 a Nodosarian shape. The shell is rough with grains of sand cemented 

 into its substance ; a structure affected by Textularia and some other 

 genera, but not by Nodosarina. It was mistaken by one of us for 

 a Nodosaria, and named N. rustica, Jones, in Morris's Cat. Brit. Foss., 

 1854, p. 37 ; and Montagu evidently had specimens (derived from the 

 London Clay) before him when he described and figured the " Nautilus 

 Kadicula," Test. Brit. p. 197, pi. xiv. fig. 6 (not pi. vi. fig. 4) ; see Ann. 

 Nat. Hist. 3 ser. vol. iv. p. 344 and p. 350. This elongated dimorphous 

 Textularia is one of D'Orbigny's Clavulinae (Clavulina communis, 

 For. Foss. Vien. pi. xii. figs. 1, 2) ; other " Clavulina? " are elongated 

 Uvigerinse and Yalvulinse (see Ann. Nat. Hist. 3 ser. vol. v. p. 469). 

 This little Foraminifer is very common in the London Clay and in 

 some other Tertiary deposits; and it still lives in the Mediterranean. 



Fig. 8. Nodosaria Badenensis, D'Orb. For. Foss. Yien. pi. i. 

 figs. 34, 35. This is a modification of the usually more regular JSf. 

 Maphanistruni, Linn. ; indeed, the increase of size in some of the 

 chambers is so variable, that there is no real ground for the separation 

 of this from the next form, with which it is associated in considerable 

 abundance in the London Clay, and several other Tertiary deposits. 

 The specimen figured is a fragment. 



Fig. 9. Three chambers of the long, cylindrical, ribbed Nodosaria 

 Haplianistrum, Linn., the same as N. Bacillum, Defrance, N. aqualis, 



