170 FAMILY LAGENIDA. 



pulchella ; and other connecting links are met wdth. In large, well-developed individuals, 

 whether of typical or of dimorphous growth, the surface of the segments is generally marked 

 by elevated costa? running parallel to the axis of the shell (ex, fig. 138) ; but in place of 

 these we not unfrequently find the surface rendered hispid by prickles, especially in speci- 

 mens brought from great depths. In these forms of exogenous deposit there is a manifest 

 parallelism to Lagena and Nodosarina. In specimens of more feeble growth, however, the 

 ribbing becomes obsolete on the newer chambers ; and in some of the dimorphous forms it 

 is scarcely perceptible even on the earliest. 



267. Affinities. — On the principles of classification here adopted, the nearest relation- 

 ships of JJvigerina are obviously to Polijmorplnna and Nodosarina. We shall hereafter find, 

 when we come to speak of Texfularia, that the dimorphism of Uvic/erina is very strikingly 

 paralleled in that type, as it is also in Valvuliiia (■] 221); but the relation thus indicated 

 is one of analogy or isomorphism, not of aflinity. 



268. Geoi/rapltical Bislribidion. — The home of this type seems to be in warm seas, at 

 depths of from 100 to 300 fathoms ; it ranges, however, in regard to depth both upwards 

 and downwards, and in regard to latitude towards both polar and equatorial regions, being 

 found in shore-sands from all quarters of the globe, and also in deep-sea dredgings and 

 soundings. 



269. Geolofjical Distribution. — ^This genus has not been recognised in any deposit older 

 than the Middle Tertiary period ; but it thenceforward presents itself abundantly in various 

 localities. 



