234 FAMILY GLOBIGERINIDA. 



Mr. Carter's figure and description to follow a regular spiral plan throughout (d ), the spire 

 being continuous from the base to the apex of the cone ; and the chamberlets are simple as 

 in P. corrit(/ata, not again subdivided as in P. lenticularis. The upper part of the cone is 

 covered by an exogenous deposit of shell-substance (c, 1), which gradually subsides, about 

 half way down the cone, into granulations that project in rows from the septal bands, forming 

 a superficial limbation. On the other hand, the chambered structure of the interior of the 

 cone is strengthened by solid columns of a somewhat conical form (e, 4), the apices of which 

 are directed to the interior of the cortical layer, whilst their bases form large tubercles which 

 project from the basal surface ( f, 1). These columns are obviously analogous to those which 

 we have seen to be formed in Tinoporus haculatus by the accumulation of solid shell-substance at 

 the meeting angles of the septa which divide tlie piled-up chambers (^ 397) ; and the whole 

 description given by Mr. Carter justifies the belief that the chambered structure is essentially 

 the same in the two cases. Now, from what we have already seen in Tinoporus, and from 

 what we shall hereafter find to be the case in OpercuUna, Nunimulina, and Orbitoides, it may 

 be stated with certainty that the presence or absence of these sohd columns is a character so 

 extremely variable as not in itself to have even a specific value. And when the account 

 already given of the recent Patdlina is taken in connection with the facts formerly stated 

 in regard to the varieties in plan of growth shown by OrhitoUtes and OrhicuUnn, it becomes 

 obvious that the persistence of the early spiral succession through the whole period of 

 increase is not in itself a character of sufficient importance to constitute a specific differen- 

 tiation ; more especially as we are informed by Mr. Carter that the spire is subject to irregu- 

 larities, sometimes becoming double. The subdivision of the superficial portion of the 

 chambers of P. lenticularis, however, if it should prove to be a constant character of that 

 type, and to be altogether wanting in P. Cooki, would be held sufficient for the specific 

 differentiation of the former from the latter. 



406. Affiniiies. — So far as the minuteness of the recent examples of this genus, and the 

 imperfect preservation of its larger fossil specimens, allow us to form an opinion of its affini- 

 ties, these appear to connect it, on the one hand, with those aberrant forms of the Rotaline 

 series in which the spiral tends to give place, at an earlier or later period, to the cyclical plan 

 of growth ; whilst, on the other, it seems related to the minutely sub-divided spiral and 

 cyclical forms of the Nummuline series. There is something in its sharply defined trochoid 

 cone which strongly reminds us of the typical Pulvinuliins ; and although it is only in the 

 P. Cooki that the spiral plan of growth is maintained throughout, yet the vermiculate spiral 

 in which P. comyata often commences no less strikingly resembles that of the complanate 

 forms of Pulviniilina. And it seems further to be allied to that genus, rather than to Discor- 

 hiiia or to PianorbuJina, in the fineness of the porosity of its shell. To Discorhina, how- 

 ever, it is specially related in the occupation of its deep umbilical cavity by an aggrega- 

 tion of secondary chambers, which thus conceal its inferior lateral surface ; and in its general 

 plan of growth it may be considered as specially related to Ci/nibalopora. The relation of the 

 large, highly-developed, fossil forms oi Patelliiia to the conical, outspread examples oi Tinoporus 

 seems to be exceedingly intimate ; the essential difference appearing to lie in the limitation 

 of the secondary chamber-growth to one side, and in the distinctness of that growth from the 

 layer in which the organism originates. At present it can scarcely be said with certainty what 



