50 HENRY B. BRADY. 



The adoption of the subordinate generic terms, quoted 

 from various authors in the foregoing paragraphs, as the basis 

 of an arrangement of the Lituoline group, is not to be 

 regarded as an indication of any material alteration of the 

 views I have expressed in many previous papers, both alone 

 and in conjunction with my friends Professors W. K. Parker 

 and T. Rupert Jones. On the contrary, every new discovery 

 seems but to furnish a missing link in a chain already nearly 

 continuous. But though it is certainly impossible to draw a 

 sharp line at any point marking a distinct stage of differen- 

 tiation, there is none the less a necessity for distinguishing 

 by name the central forms of the principal terms of the 

 series, and these are what must stand as " species." Under 

 such circumstances, or perhaps under any, " genus" is little 

 more than a term of convenience. 



With this explanation I would suggest the following scheme 

 for the arrangement of the Lituoline family. It is in part 

 adopted from that proposed by Professor von Reuss. No 

 new terms have been introduced, its object being to set in 

 order and give definiteness so far as our present knowledge 

 extends to generic names already more or less in use, and so 

 to avoid the confusion of fresh terminology. That the distinc- 

 tions are to some extent artificial may be freely admitted, but 

 any other arrangement that suggests itself is open to the 

 same objection. 



General Characters. — Exterior more or less rottghly 

 arenaceous; septation of the polythalamous forms 

 rudimentary or imperfect. 



A. Non-labyrintMc. 



a. Adherent by its flat surfac& . . . Placopsilina, d'Orb. 



b. Adherent, columnar, attached at one end Haliphi/sema, Bow. (?). 



c. Tree, uniserial, monilirorm, never spiral Reophax, Montfort. 



d. Tree, partially or entirely spiral, nauti- 



loid or crozier-shaped . . . Haplophragmium, Reuss. 



B. Chamber-cavities subdivided or labyrinthic. 



a. Adherent by its flat surface . . . Bdelloidina, Carter. 



b. Adherent, subcylindrical, columnar, at- 



tached at one end .... Folyphragma, Reuss ( ?). 



c. Free, uniserial, straight or arcuate, 



never spiral Haplostiche, Reuss. 



d. Free, partially or entirely spiral, nauti- 



loid or crozier-shaped . . . Liiuola, Lamarck. 



Gewws— PLACOPSILINA, d'Orhicjny. 

 General characters. — Test adherent ; composed of a single 

 convex, tent-like chamber, or of many such segments vari- 



