590 DE. CAEPENTEE'S EESEAECHES ON THE FOEAMINIFEEA. 



Fig. 4. Disk of Philippine variety, as seen on its growing side, with the origins of 

 the spines ; the last half whorl is here apparent, the newest chambers having 

 only their own proper walls, whilst those which preceded them are more and 

 more overgrown by the 'intermediate skeleton,' in which they gradually 

 become imbedded ; the surface of the disk shows the usual punctation, with 

 an average development of tubercles ; that of the spines is furrowed. Magni- 

 fied 25 diameters. 



Figs. 5, 6, 7. Young Calcarince, showing their ordinary aspect. Magnified 20 dia- 

 meters. 



Figs. 8, 9. Hispid varieties of Philippine Calcarince (see also Plate XX. fig. 6). Mag- 

 nified 30 diameters. 



Figs. 10, 11. Portions of figs. 8 and 9 more highly magnified: in fig. 10 it is seen that 

 the spines are tubular, being formed around the pseudopodia as they issue 

 from the passages in the shell. Magnified 60 diameters. 



Fig. 12. Ideal representation of Calcarina laid open; showing the unsymmetrical or 

 ' turbinoid ' disposition of the spire (its apex being placed downwards for 

 more convenient display) ; the Rotaline aspect of the last-formed chambers, 

 and the row of pores along the inner margin of the septal plane, which con- 

 stitutes the only aperture of the last chamber ; the manner in which each 

 turn of the spire is overgrown by the exogenous deposit~forming the ' inter- 

 mediate ' or ' supplemental skeleton ' which fills up the whole interior of 

 the cone, and conceals all but the last-formed portion of the spire; the 

 penetration of this ' supplemental skeleton ' by canals, which originate on the 

 outside of the proper walls of the chambers, and pass in a somewhat radiating 

 direction towards both surfaces of the disk, separated at intervals by non- 

 canaliferous cones, whose bases appear externally as elevated tubercles ; the 

 connexion of the spines with the ' supplemental skeleton,' from which the 

 older spines receive new investments at every turn of the spire; and the 

 extension of the canal-system into the spines, on the furrowed depressions of 

 whose surface it opens at numerous points. 



PLATE XX. 



All the figures in this Plate refer to Calcarina Spengleri. 



Fig. 1. Section of the disk taken through the axis of the spire : , a 1 , a 2 , 3 , a 4 , successive 

 whorls transversely divided ; b, the proper wall of the last-formed chamber, 

 not yet consolidated by exogenous deposit; <?, row of pores at -the inner edge 

 of the septal plane, constituting the only communications between the 

 chambers; d, d, canals passing through the supplemental skeleton to the 

 surface of the disk; e, e, non-canaliferous portions of the supplemental 

 skeleton. Magnified 50 diameters. 



