FAMILY 29. HETEROHELICIDAE 229 



B. Later chambers variously arranged. 



1. Uniserial. 



a. Test elongate, compressed, chambers becoming high. 



Plectofrondicularia. 



b. Test broad, compressed, chambers becoming low, some- 



times annular Pavonina. 



2. Multiserial. 



a. Test in later development spiral Pseudotextularia. 



b. Test in later development spiral, later with numerous 



globular chambers in one plane Piano globulina. 



c. Test in later development with a fan-shaped series directly- 



after the biserial stage Ventilabrella. 



3. Triserial Eouvigerina. 



III. Early stages ti'iserial. 



A. Triserial throughout Pseudouvigerina. 



B. Triserial in the young, later uniserial S I pho gene vino ides. 



IV. Test wholly uniserial. 



A. Early portion compressed, aperture without a lip. 



1. Early portion concave Amphimorphina. 



2. Early portion somewhat compressed, not concave. 



Nodomorphina. 



B. Not compressed, apertui'e with a lip Nodogenerina. 



Subfamily 1. Heterohelicinae 



Test in the early stages distinctly planispiral, later chambers 

 biserial; aperture large, at the inner margin of the chamber. 



Genus HETEROHELIX Ehrenberg, 1843 

 Plate 33, figure 1; plate 34, figure 1 



Genotype, by designation, Spiroplecta ainericana Ehrenberg 



Heterohelix EHRENBERG, Abhandl. k. Akad. Wiss. Berlin, 1841 (1843), 

 p. 429. 



Spiroplecta Ehrenberg, Bericht. k. Akad. Wiss. Berlin, 1844, p. 75 (geno- 

 type, by designation, Spiroplecta americana Hhrenbekg — Heterohelix) . 



Test in the early stages planispiral forming a considerable 

 part of the test, the few adult chambers biserial ; wall calcareous, 

 perforate, thin ; aperture large, on the inner margin of the last- 

 formed chamber, median. 



Cretaceous. 



