476 On the Nomenclature of the Foraminifera. 



to, or embracing the exterior of, the old cells. These added 

 cavities do not appear to communicate with the surface, the 

 shell-wall being thick. The stolon-tubes arising from the sides 

 of the original innermost chambers pass by the sides of the great 

 medial cseca, and terminate in small, subglobular, peripheral 

 cells, opening by simple round apertures on the outer surface. 

 The junctural interspaces are hidden in this highly complicate 

 form, which is the D. cylindracea of Lamarck. Pohjtrype elon- 

 gata of Defrance is a more attenuate variety. 



These larger cylindrical forms, which are not uncommon in 

 the Grignon deposits, present essentially the same conformation 

 as the simpler varieties before described, with the exception, 

 however, of the peculiar added structure, consisting of large 

 csecal cells and numerous smaller cells, the latter arranged quin- 

 cuncially over the whole of the exterior of the cylinder, and 

 hiding the junctural interspaces, which still remain visible in the 

 interior. The cylinder narrows itself towards the ends, thus 

 becoming fusiform. 



The surface of the external or superadded series of chambers, 

 when perfect, is smooth, and marked by the regularly-arranged 

 round apertures ; but when worn (as is very frequently the case), 

 the outer cell-walls disappear, leaving smooth cup-shaped hol- 

 lows, each perforated at the bottom with the canal of the con- 

 necting stolon. The quincunx gives visually a hexagonal or 

 honeycombed appearance to the worn surface. When the pas- 

 sages between the first chambers and the exterior exist as tubes 

 only (as in D. Bamhusa), the worn surface has a pitted aspect; 

 and in other varieties several different complications of large and 

 small apertures are seen in worn specimens. In the figure of a 

 very large specimen of D. cylindracea, from Grignon, given by 

 Goldfuss (pi. 12. f. 4), we see carefully drawn a quincuncial 

 lattice of the worn cells, with small interspersed openings of 

 supernumerary pseudopodial passages from primary cells. This 

 character is not given in Defrance's figures, nor have we yet met 

 with it in our own specimens. 



Lamouroux figures and describes a large specimen under the 

 name of Reteporites digitalia (Polyp, p. 44, pi. 72. f. 6-8). 



Michelin's Uteria Encrinella (Icon. Zooph. p. 177, pi. 46. 

 f. 26), from the Eocene beds of Cuisse-Lamotte (Oise) is a spe- 

 cimen of D. cylindracea, presenting an unusual shortness of 

 cylinder, evidently perfect and unworn. 



Michelin's Turbinia graciosa (Icon. Zooph. p. 177, pi. 46. 

 f. 15), from Grignon and Cuisse-Lamotte, appears to be a short 

 D. cylindracea, which, after having developed a few normal 

 circles of compound cells, was finished off with a converging 

 series of less complex cells. 



