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



3rd edit. vol. ii. pt. 5. p. 94, pi. 29 1 . f. 29) as Hijmenocyclus* 

 Faujasii (Lycophris Faujasii, Defr.), consists of a plano-convex 

 disk, about half an inch wide, with a central mamilla on the 

 upper (convex) side. Its vertical section shows two horizontal 

 series of chambers : the upper and largest appear to be the sub- 

 quadrate subdivisions of the primary annuli (seen also in the 

 horizontal section, which shows four periodical stages of growth 

 around the undivided primordial cells) ; the lower set may be 

 umbilical cells imbedded in a copious growth of exogenous shell- 

 matter. These characters point it out as a gigantic ally of 

 variety No. 4 above described (Orbitolina annularis). It is very 

 closely allied to, if not identical with, O. lenticularis, Blumenbach 

 (O. lenticulata, Lamarck). This latter is figured by Bronn (Leth. 

 Geogn. 3rd edit. pi. 29 2 . f. 22) after Lamouroux (Polyp, pi. 72. 

 f. 13-16), and presents similar features, though obscured by 

 fossilization and wear. The O. lenticularis is from the Aptian 

 beds of the Perte du Rhone ; and some specimens are carefully 

 figured and described by Delucf in the Journ. Phys. lvi. p. 344, 

 figs. 1-6. These are concavo-convex, about \ inch in diameter, 

 and have a structure almost identical with that of the little 

 recent O. annularis from Australia, both as to the smooth upper 

 and radiate lower surface, and as to the "engine-turned" arrange- 

 ment of the subdivided primary chambers. In the larger and fossil 

 form we appear to have more than one tier or layer of cells. From 

 Deluc's remarks we may conclude that some individuals by their 

 porous surface show a limbation of the septal edges. We cannot 

 separate Deluc's specimens from O. concava, on one hand, and 

 O. annularis on the other. A short notice and some carefully exe- 

 cuted figures of Orbitolina lenticularis are to be found in Pictet 

 and Renevier's e Paleontologie Suisse ; Fossiles du Terrain Ap- 

 tien/ p. 166, pi. 23. figs. 3«-3/. 



The Cyclolina cretacea, D'Orb. For. Foss. Vien. p. 139, pi. 21. 

 f. 22-25, judging by D'Orbigny' s description and figures, is an 

 excessively outspread, thin, discoidal variety, presenting an ex- 

 treme form of O. annularis, of which it is in essential features 

 an exact counterpart, consisting of a series of perfect annuli, 

 with very little development of the umbilical cell -growth. 

 The shell is finely perforate, the perforations being best seen on 



* This name is proposed by Bronn to take the place of " Orbitoides," 

 which he rejects as a " hybrid word." D'Archiac, in describing his Or- 

 bitolites media, expresses his belief that it is the same as Faujas's Numis- 

 male. D'Orbigny correctly places D'Archiac's species under Orbitoides, 

 and incorrectly includes Faujas's also. Bronn follows D'Orbigny in this, 

 and makes O. Faujasii a type for Hymenocyclus. 



f His fig. 2, however, evidently gives a somewhat mistaken view of the 

 structural details of the vertical section. 



