300 Messrs. Parker and Jones on 



spread, rhomboidal, and suboblong Textilariiform variety is 

 seen in pi. xxxii. il. figs. 18 & 20, termed " Grammostomwn 

 tessera'''' and '■'■ Pleuritesl americanus.'''' 



PI. XXVIII. figs. 31, Heterostomum cyclostomum, and 33, 

 Grammostomum platytheca, are young, broad, coarse-shelled 

 Textilario} gihhosce. Fig. 32. See above. _ Figs. 34-42 a, 

 variously named '^Eotalia;'^ (including Rotalia glohidosa^ 1838, 

 figs. 40,41), are so many individuals of Glohigerina cretacea^ 

 D'Orb., an outspread flattish variety of Gl. huUoides, D'Orb., 

 smooth in the youngest (41, 42), coarser and prickly in older 

 specimens. 



• Fig. 43, Planulina om'phalolepta [PI. turgida^ 1838), is a 

 small and somewhat complanate Cristellaria rotulata (Lamk.) 

 or feebly keeled Or. cultrata (Montf.). Fig. 44, PL anmdosa, 

 is a still smaller specimen. Fig. 45, a, b, PI. odo7itophcena^ 

 is Grist, cultrata (Montf.). Fig. 45 a has tear-like and ridgy 

 exogenous growths of shell-matter near the umbilicus, but no 

 umbo. Fig. 46, PJ. liexas {Rosalina glohularis'^, 1838), is Or. 

 cultrata with a small keel. Fig. 47, Rotalia proitexta^ is a 

 produced suboval individual of Crist, cultrata. Fig. 48, Pla- 

 nulina adspersa^ is probably a small Or. cultrata or rotulata : 

 in fact figs. 43-48 show various stages and conditions of 

 growth of the common Cristellaria of the Chalk in its umbili- 

 cate condition, and with more or less of a keel or crest. 

 Fig. 49, PI. umhilicata^ also 54, Cristellaria megalomphala^ 

 and 55, Cr. anglica^ are limbate specimens of Cr. cultrata — 

 that is, having the shell thickened over the septal lines. 



Figs. 50, Rotalia lenticulina, 51, R. londinensis, and 52, R. 

 lepida^ are small individuals of Planorhilina atnmonoides. 



Fig. 53, R. jiictal This is Pulvinulina Micheliniana 

 (D'Orb.), seen from its flat (upper) spiral face. The same 

 species is represented in pi. xxvii. fig. 52, by a rather larger 

 specimen [^'■Planidina picta'''') from the Chalk of Meudon, 

 viewed through the vertical thickness of the shell from its 

 high umbilical (lower) face. This belongs to a large family 

 of Rotaline Foraminifera, which group themselves around 

 Pulvinidina repanda (Fichtel & Moll). It belongs more es- 

 pecially to the subgroup of which P. Menardii is the type. 

 This attains its best growth at about 100 fathoms in the 

 existing seas, but lives well at abyssal depths, even at more 

 than two miles depth ; whilst, on the contrary, in shallow 

 water it degenerates into hizarre varieties. D'Orbigny's Ro- 

 talia crassa, figured on the same plate (Mem. Soc. Geol. Fr. 

 iv. pi. 3. f. 7, 8), is also a variety of Pulvinulina Menardii. 

 These are found in existing seas under the conditions men- 

 tioned above, and are abundant in the Gault, Chalk-marl, and 

 Chalk. 



