CHAPTER IX. 



OF THE FAMILY GLOBIGERINIDA. 



270, Under the general designation Globigerinida we bring together, for the reasons 

 already stated, all those hyaline or vitreous Foraminifera which have their shell-substance 

 coarsely perforated for the exit of pseudopodia, so as to resemble that of Globifferina ; a cha- 

 racter by which they are differentiated from the Lagenida on the one hand, and from the 

 NuMMULiNiDA ou the other. They are further differentiated from the former of these families 

 by the form and character of their aperture ; for although there are instances in which the 

 chambers communicate with each other, and the last chamber with the exterior, by circular 

 pores, yet this is only in aberrant forms of the group ; and the typical aperture is a crescent, 

 which may either be contracted to a narrow fissure, or which may open-out so as to have 

 the proportions of a gateway. There is not a like difference in the form of the aperture 

 between Glodi^erinida and Numinulinida ; but generally speaking, it is of much larger size, so 

 as to permit a much freer communication between the segments of the body in the former 

 group than in the latter. 



271. The series of foi^ms whose agreement in these fundamental characters may be 

 considered as justifying their association in the same family, presents varieties of configura- 

 tion, dependent upon differences in their plan of growth, which are even greater than those 

 we have encountered in the preceding case ; and widely separated places have accord- 

 ingly been assigned to them by those Systematists who adopted " plan of growth" as the 

 basis of their arrangements. Thus, in the classification of D'Orbigny, our genera would be 

 distributed as follows : 



Order I. — MoNosTisGUEs. Orbulina, Ovulites, Spirillina. 



Order II. — Cyclostegues. Tinoporus (Orbitohna, L'Orb.), Patellina. 



Order IV.^ — H^licostegues. Globigerina, Carpenteria, PuUenia (part of Nonionina, 

 D'Orb.), Bulimina, Chrysalidina, Rotalina (including Rosalina, Pla- 

 norbulina, Anomalina, Calcarina, and part of Asterigerina, B'Orh.) 



Order V. — Entomostegues. Cassidulina. 



Order VI. — Enallostbgues. Textularina, Cuneolina. 



Order VII. — AGATHiSTtiGUES. Sphseroidina. 



