232 



FAMILY GLOBIGERINIDA. 



vary from that of a high to that of a depressed outspread cone ; and the diameter of the Indian 

 specimens ranges between l-8th and 2-3rds of an inch, the smallest being relatively the highest. 

 The general plan of structure of this fossil corresponds with that of the recent Patellina ; the 

 cone being formed externally of a succession of annular segments subdivided by transverse 

 partitions into chamberlets (d, 3) ; whilst its interior is more or less completely filled up by a 

 secondary umbilical growth. But there are two very important differences in detail. In the 

 first place, each of the chamberlets of the annular series is again partially subdivided into four 

 or more, by septa which project from tlieir external wall, but which do not extend above half- 

 way towards the interior (Fig. XXXVII, d,2,3, g,1,2); so that the surface of the cone 



Fig. XXXYIT. 



Patellina lenticularis : — A, B, c, couical surface, basal surface, and edge view, one half larger than the natural size: 

 — D, Diagram showing 1, arrangement of chambers at the centre or apex, which is at first more or less confused, and then cyclical ; 

 2, external or reticulated chamber-lajer; 3, subjacent or large chamber-layer; 4, engine-turned arrangement of chambers 

 below the last-mentioned layer : — e. Magnified view of portion of patulous surface, to show the arrangement of the ends of 

 the columnar chambers in tiie form of granulations : — f, Horizontal section, showing, 1, reticulated layer ; 2, large chamber- 

 layer ; 3, colunuiar chamber-structure : — G, Vertical section of half the fossil, showing, 1, reticulated layer externally ; 2, large 

 chamber-layer; 3, columnar chamber-structure. — After Carter. 



shows a very minute subdivision of its external layer, whilst the removal of this brings into 

 view the larger chamberlets formed by the primary subdivision of the annulus. This 

 arrangement is represented in the accompanying figures, which are copied from Mr. Carter's 

 somewhat diagrammatic delineations. I feel certain, however, that in my own specimens 

 the large chambers of the peripheral annuli are prolonged inwards in a radial manner much 

 further than Mr. Carter represents them, and that they communicate freely with those 

 which fill up the hollow of the cone, instead of being terminated on their inner side by 

 transverse walls. The umbihcal growth consists of an aggregation of compressed chambers, 

 which are described and figured by Mr. Carter (d, 4) as having an engine-turned arrange- 

 ment ; and these rest one upon another in columnar piles, more or less completely filling 

 the cone, and sometimes extending even beyond its base, so as to give this a convex surface. 

 This surface is marked by tubercular granulations (e), which probably result (like those of 

 Tinojwrus, ^ 392) from septal limbation. In my own specimens of this fossil, the 



the Orhitolinm of Lamarck and subsequent writers are to be referred to the genus Tinoporus, and what 

 to the genus Patellina ; since their forms are derivable from those characteristic of either type, and 

 their internal structure is seldom sufficiently well preserved to afford the means of positive diagnosis. 

 I am inclined to believe, however, that all those conoidal, lenticular, or discoidal forms which exhibit a 

 more or less distinct animlation are true Paiellinte. 



