114 Messrs. W. K. Parker and T. R. Jones on the 



deposits rich in Cristellaria) we have the link with the Margi- 

 nuline variety of Nodosaria Raphanus, especially in the Viennese 

 specimen, which is narrow -chambered, pinched, and umbilicate, 

 like the crozier-part of a Marginulina. This linking is not only 

 shown by the form, the aperture, and the general structure of 

 the shell, but markedly in the style of ornament. The orna- 

 mentation of ribs is highly characteristic of the Nodosarine 

 group. In Nodosaria the riblets are often fully and symmetri- 

 cally developed; in some Marginulinae the rib on the convex 

 border surpasses its fellows; in Cristellaria it is often the only 

 remnant of these ribs ; but in some varieties, as in Robulina 

 echinatu, D'Orb., R. ornata, D'Orb., and especially in R. Arimi- 

 nensis and FichtePs Nautilus costatus, the rib-ornament still 

 bears evidence of the relationship mutually borne by these 

 diversely modified forms. Hence one of the grounds for the 

 foundation of the comprehensive genus Nodosarina*, intended 

 by us to embrace the Nodosarice, Cristellaria, and all the inter- 

 mediate and associated varieties. Indeed, we see as yet no 

 essential characters in this protean group whereby more than 

 one real species can be established, although we have examined 

 thousands of forms, not to say individuals, from the Permian, 

 Triassic, Liassic, Oolitic, Cretaceous, and Tertiary deposits, as 

 well as from deep and shallow seas of all parts of the world. 



20. Nautilus acut-auricularis. Page 102, pi. 18. figs. g-i. 

 " Recent : zoophytic concretions, Mediterranean." A sub- 

 globose or ovoid Cristellaria, with numerous smooth, narrow, 

 flush chambers, slightly keeled. This is a variety intermediate 

 between C. Calcar and Defrance's Saracenaria Italica. It is 

 also nearly related to C. arcuata, D'Orb. (For. Foss. Vien. pi. 3. 

 figs. 34-36). This appears to be a rather rare and small form. 

 Fichtel and MolPs reference to Soldani, Testaceogr. vol. i. p. 61, 

 pi. 49. fig. x y for this form, is correct. 



21. Nautilus Crepidula. Page 107, pi. 19. figs. #-z. "Recent : 

 Leghorn coast." A delicate, elongate, Marginuline, flattened 

 Cristellaria. This variety, which by innumerable Unkings passes 

 into C. Calcar , is so readily modified by external conditions as 

 perhaps not to be represented by any two perfectly similar indi- 

 viduals. D'Orbigny's C. cymboides (For. Foss. Vien. pi. 3. figs. 

 30, 31) is almost an exact counterpart of Fichters figure; but 

 in the former the coil is more open. C. compressa, D'Orb. (loc. 

 cit. figs. 32, 33), and C. lanceolata, D'Orb. (/. c. figs. 41, 42), as 

 well as Montfort's "Astacole crepidule," which is Blainville's 

 and Defrance's " Crepiduline astacole " (Diet. Sc. nat. pi. 19. 

 fig. 8), are similar attenuate, but keeled, varieties of Cristellaria 

 Calcar. 



* Annals, 1869, iii. p. 477. 



