76 THE FOEAMINIFERA 



fragment of almost any of the shells belonging to 

 this family in a transparent medium, like Canada 

 balsam, the white appearance gives place to a yel- 

 lowish brown or horn colour, and the absence of the 

 tiny tubules, which pierce the shell- wall of the 

 hyaline forms, will be at once noticed. 



In discussing the various members of this family 

 it will presently be seen that this division of the 

 Foraminifera exhibits a great many types of shell- 

 building, and presents isomorphous analogues with 

 those of the other groups of the arenaceous and the 

 hyaline Foraminifera ; and in fact are only dis- 

 tinguished from some other genera outside the family 

 by the imperforate and porcellanous nature of the 

 shell. 



A certain degree of relationship with one another 

 may be found amongst the various genera belonging 

 to this family. The simplest types are those of the 

 genera SqtiamuUna, which has a single-chambered 

 plano-convex test, and Cornuspira, which forms 

 a non-septate tube coiled in one plane. Starting 

 from Squamulina, a series of such chambers joined 

 end to end gives rise to Nubecularia ; or, if non- 

 septate and sending off radiating tubes, to a form 

 like Calcituba, an isomorph of the arenaceous genus 

 Astrorliiza. In SquarnuUna again we may discover 

 relationship with certain wild-growing Miliolince and 

 also with the subspherical but septate Nuhecnlaricc. 



In the MiLiOLiNiN-E the fundamental form may be 

 considered a globose segment, which afterwards, as 

 by a modification of a spiral tube like Coi'nusjjira, 



