398 MB. S. Oo EIDLEY ON VARIATION IN 



columella is composed of minute, rather contort, and sublaminar 

 papillae, to which the interior and inferior terminations of some 

 of the secondary and tertiary septa (and rarely the primary also) 

 contribute a very thin horizontal laminar ridge or foot, which is 

 minutely dentate in the case of the secondary and tertiary septa. 

 This ridge is a " paliform lobe " in a most rudimentary condition, 

 and in some cases can be called no more than the inward pro- 

 longation of the lower margin of the septa. The septa occur in 

 four cycles, of which the fourth is frequently wanting ; the pri- 

 maries rise nearly 1 millim. above the wall, slope off gradually 

 towards the middle of the calicle, and their inner edge falls 

 almost perpendicularly downwards from a point which is about on 

 a level with the margin of the wall, where the septum is about 

 1"25-1'5 millim. wide,: the sides are finely striated ; the seconda- 

 ries may project about '3 millim. above the margin, but both these 

 and the tertiaries scarcely project inwards at their upper termi- 

 nation at all, but slope off gradually by concave margins until 

 they join the columella as above described ; the quaternaries also 

 project but slightly into the interseptal spaces, and either fall 

 almost perpendicularly at once into these spaces, where in some 

 cases they may be seen extending a horizontal lamina towards 

 the columella at a considerable depth, or attach themselves late- 

 rally to the adjoining septa. All the septa resemble tissue-paper 

 in their thinness, and the secondary, tertiary, and quaternary 

 have fine but prominent granules on their faces ; the primaries 

 and secondaries and the upper parts of the rest have the margin 

 entire ; the subhorizontal inner portion of the tertiaries is finely 

 dentate. Verrill's specimens and those in the British Museum 

 from Punta Arenas agree with each other, and differ from the 

 Malacca specimens in the granulated (not striated) condition of 

 the primary septa, and the variability in extent of the columella, 

 and in the occasional minute denticulation of the edge of the 

 primary septa. Even allowing for individual differences and the 

 possible influence of depth, this species must be distinguished 

 from papuensis by the inequality of the costae, the minute 

 numerous papillae of the columella, and the rudimentary condi- 

 tion of the paliform lobes. 



I would call attention to two points in this species, viz. (1) the 

 variability of the costae (a) as regards actual prominence, viz. from 

 practical absence to moderate development, and (&) as regards 

 relative prominence, viz. from a subequal condition to one in which 



