Introduction to Animal Morphology. 51 



perceptible except by limiting the pseudopodia to one 

 spot of origin (Lieberkiihnia). 



Its texture may be porcellanous (white, opaque), with a 

 terminal opening, or vitreous and pierced by holes scattered 

 over the surface. In the former case, pseudopodia project at 

 the terminal opening ; in the latter, they protrude over the 

 whole surface. The shells may be one-celled oval (Ovulina), 

 spiral (Cornuspira), or flask-like (Lagena), or many-celled, 

 produced by continuous budding, but the whole mass makes 

 up one persona {Hacckel). These chambers may succeed 

 each other in a straight line* or in alternate series on two or 

 three alternate axes, either forming a spiralf or notj ; or they 

 may be successive, forming a spiral which may be discoidal§ 

 or inequilateral II ; or the chambers may be wound on an 

 axis, each embracing half its circumference^ ; or, lastly, they 

 may be in complete circles with a porous circumference,*'*' or 

 else irregular.ff The terminal opening may be round 

 (Cornuspira), oval (Guttulina), crescentic (Spirulina), semi- 

 circular (Globigerina, Fig. 2), reniform (Triloculina), linear 

 (Fusulina), or it may consist of several series of pores 

 (Polystomella). 



Each chamber may have a complete wall, or may 

 be closed by the wall of its neighbouring compart- 

 ment. They communicate by single or multiple pores, 

 and each chamber may also have radial interseptal 

 canals traversing the septa to the outer edge. The 

 chambers, in some, form concentric rings around a 

 central cell (the nucleus), each whorl being a conti- 

 nuous tube of which the chambers are regularly serial 

 dilatations with narrow interspaces. The chambers 



* Stichostegia, D'Orbigiiy, \\ H. Turbinoidea. 



t Entomostegia, D'O. f Agathistegia. 



+ Enallostegia. ** Cyclostegia. 



§ Helicostegia Nautiloidea. tt Soroidea, Schultze. 



