68 THE MICROSCOPE. May., 



Stephanium are marked by basal feet or loQg, thick 

 spines, the former having three, the latter four. In the 

 Fam. Semantida there are two rings (see Fig. 21), one 

 horizontal, the other joined to it in a vertical position. 

 Cortiniscus and Stephaniscus have feet on the horizon- 

 tal ring, the former three, the latter four. The other 

 genera lack such feet and are separated by the number 

 of pores inside the horizontal ring. The student might 

 suppose that in such cases the forms had no single large 

 opening and were therefore not Nassellaria, but the space 

 inside the basal ring is regarded as such, as it is found 

 entirely ojjen in other genera, and the mouth is assumed 

 to be partially closed by a lattice plate. In another 

 order, that of the Cyrtoidea, we shall find the pores in 

 this mouth plate so small that at first it will be hard for 

 the student to distinguish the forms from those of the 

 Spumellaria by any such mark as that of a single wide 

 opening. The general shape of the form, however, will 

 show him that such forms do not belong to the Spum- 

 ellaria, the end which is said to have a mouth closed by 

 a lattice plate being different from the other end. In 

 the Fam. Coronida there are also two rings, but they are 

 both vertical meridional rings, intersecting like two 

 hoops crossed at right angles (see Fig. 22) and there is 

 usually a horizontal ring as well. The genera are dis- 

 tinguished by the number of gates or large openings 

 formed by the intersections of the rings. In Podocoro- 

 nis only two of the gates are basal, in Tristephanium 

 four, the others, in each case, being lateral, that is open- 

 ings made by the intersection of the vertical rings. In 

 the Fam. Tympanida there are two parallel horizontal 

 rings (see Fig. 23) and these are connected by a vertical 

 ring and sometimes by two vertical rings or more. The 

 joinings of these horizontal rings are also called colu- 

 mellse or little columns. Microcubus has four of these 



