FORAMINIFERA— HERON-ALLEN AND EARLAND. 105 



a liypertropliiecl condition, with a rough shell-wall. C. lens, on the other hand, 

 presents internal features which differentiate it widely from the type. The central 

 cavity is furnished with radiating extensions, projecting to within a short distance 

 of the periphery, or — to put it in another form — the peripheral wall extends in 

 radial flanges almost to the centre of the cavity. This feature appears to us to 

 connect the genus with Tliolosina, which, though normally a thin-walled sub- 

 spherical shell, tends to form accessory chamberlets round the peripheral edge, 

 which, though not visible externally, are exhibited when the shell is laid open, 

 as in the figui'e given by Goes (G. 1894, ASF. pi. vi, fig. 215). 



Like most of the arenaceous Foraminifera, Crithionina, though normally free, 

 readily adopts a sessile habit. C. mamilla is rarely found in any other condition, 

 and even the occasional free specimens with which one meets have probably 

 become detached from a host. Nearly all the other species which occur in the 

 gatherings are found in both free and sessile condition. 



The building material used by Crithionina, is, as already mentioned, usually 

 fine sand. Ferruginous cement is never employed, but there appears to be a 

 constant tendency to incorporate sponge-spicules in the test ; this tendency 

 reaches its maximum in the variety of C. piswm, which was described by Flint 

 (F. 1899, RFA. p. 267, pi. vi, fig. 2) as " var. hisjnda.'' C. rugosa in our Antarctic 

 material tends in the same direction ; at Station 38 the specimens showing this 

 tendency are very characteristic. At Station 55 this form occurs both free and 

 attached. 



The genus is not represented in the deep water betw^een North Cape, N.Z., 

 and the Antarctic Continent, but is generally distributed in the shallow water 

 gatherings of both areas. 



142. Crithionina granum, Goes. 



Crithionina cjranum. Goes. 1894. ASF. p. 1.5, pi. iii, figs. 28-33. 

 Rhumblor. 1903, ZRR. p. 231, fig. 58. 

 Cushman, 1918, etc., FAO. p. 69, pi. xxvi, fig.s. 6. 7. 



Stations 3, 5, 6, 26, 38, 43, 47, 50. 



Free and attached at Station 6. Large and typical at Station 38, where the 

 specimens are of dark colour owing to the incorporation of volcanic sand. 



143. Crithionina ■mamilla. Goes. 



Crithionina mamilla, Goi's, 1894, ASF. p. 15, pi. iii, fig.s. 34-36. 



Heron-Allen and Earlaud, 1914, etc., FKA, 1915, p. 616. 



Stations 2, 6, 26, 29, 38, 48, 50, 55 (+ D.). 



The distribution is similar to that of the other species of the genus. At 

 Station 6 it occurs in abundance, and with considerable variety. Some of the 

 specimens are built round large sponge-spicules traversing the mass of the shell, 



VOL. VI. P 



