850 On the Nomenclature of the Foraminifera. 



is described under this name, similarly misapplied. This is an 

 interesting Marginuline variety of Cristellaria Calcar with orna- 

 mented septal lines, which is remarkably abundant and of large 

 size in the London Clay*. We have here doubtless a specimen 

 from that source. The pinched-in youngest chamber (taking on, 

 as it were, a Dentaline character) frequently occurs in this fossil 

 variety. San Domingo has a similar, but smaller, variety in its 

 Tertiary clays; and a still more minute form is found in the 

 clays of the English Oolites. Montagu's opinion that this is 

 related to the crozier-shell {Peneroplis planatus) figured by Plan- 

 cus is quite erroneous. (See above.) 



Maton and Kackett followed Montagu in mixing *'semi- 

 lituus'^ with '^ subarcuatulus'^ (Linn. Trans, vol. viii. p. 118), 

 and in similar mistakes. So also did Dillwyn in his ' Descrip- 

 tive Catalogue of Recent Shells,' 1817, as well as Turton, Pen- 

 nant, Fleming, &c. 



(J. /.) Supplem. p. 86. " Nautilus bicarinatus.'' Described 

 as being more arcuate than "N. subarcuatus, tab. 6. f. 5,'' 

 rounded posteriorly, and furnished w^ith two longitudinal ribs, 

 " one along the arc, and another on the opposite side.'' From 

 Sandwich. 



Prof. Williamson has placed this among the synonyma of 

 Cristellaria subarcuatula (Monogr. p. 29) ; and is most probably 

 right in thus regarding it as a narrow Marginuline Cristellaria. 



(J. g.) P. 195. " Nautilus carinatulus." Young of Cristellaria 

 Calcar. 



(K) P. 197, pi. 14. f. 6. "Nautilus Radicula." This is the 

 Clavulina communis of D'Orbigny, which is a dimorphous form 

 of Verneuilina tricarinata, D'Orb. ; that is, the trihedral arrange- 

 ment characteristic of Verneuilina proper becomes soon replaced 

 by a single series of chambers. Montagu, in his description 

 (p. 198), refers to all the characters peculiar to this form, ex- 

 cepting its roughness of surface. He evidently had in hand 

 specimens both of the form under notice and the very similarly 

 shaped Nodosaria Radicula, which differs in its aperture and its 

 terminal point, as he has noticed. From Sandwich. It is the 

 Nodosaria 7'ustica, Jones, Morris's ' Catal. Brit. Foss.' 1^54, 

 p. 38, and is very common in the London Clay. We have not 

 met with it recent on the British coast, but abundantly in the 

 Mediterranean. 



* The Marginulina Wetherellii, Jones, Morris's Catalogue Brit. Foss. 

 1854, p. 37. 



