86 THE GEOLOGIST. I| 
sea-shore of tlie south-east of England, and long thought to be recent, 
has been referred by us to the London Clay. (Annals Nat. Hist. 
3 ser. vol. iv. p. 346.) Differences iu the development of the little 
prickles constitute the chief distinctions of the closely allied forms 
D. spinulosa, Montagu, D. Adolphina, D'Orb., D. spinescens, Keuss, 
D. spinosa, D'Orb., and D. sjnnicosta, D'Orb., in all of which the 
.ongitudinal riblets, so characteristic of well-grown Nodosarinae, 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., i^. 
punctata, D'Orb., N. aculeata, D'Orb., N. Mspida, D'Orb., N. con- 
spurcata, Keuss, N. aspera, D'Orb, Dentalina aculeata, D'Orb., D. 
Jloscula, D'Orb., D. scahra, Eeuss, Marr/inulina 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 
aflbrd more distinctive characters ; but all these features are subject, 
one with another, to endless gradual transitional modifications in the 
Nodosarinse. D. sjnniilosa and its subvarieties are exceedingly com- 
mon in the London Clay and in the Septarien-Thon of Germany and 
other Tertiary beds. 
Pigs. 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- 
neuUiva), 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 aftected by Textularia and some other 
genera, but not by Nodosarina. It was mistaken by one of us for 
a Nodosaria, and named iV! rustica, Jones, in Morris's Cat. Brit. Toss., 
1854, p. 37 ; and Montagu evidently had specimens (derived from the 
London Clay) before him when he described and figured the " Nautilus 
Eadicuia," 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 {ClavuJina communis, 
For. Foss. Vien. pi. xii. figs. 1, 2) ; other " Clavulinae " are elongated 
Uvigerinse and A'alvulinae (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. Vien. pi. i. 
figs. 34, 35. This is a modification of the usually more regular iV. 
Maphanistrum, 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 
Baplianistrum, Linn., the same as N. Bacillum^ Defrance, N. aqualis, 
