STUDIES IN FOKAMINrFERA 



149 



mile upstream from intersection of Walker Creek and 

 Cameron-Clarkson road, Milam County, Texas. 



Diagnosis: Test elongate, straight, constantly biser- 

 ial in the early stage in both microspheric and mega- 

 lospheric forms. Chambers rather inflated. Sutiu-es 

 slightly depressed, subhorizontal. Wall calcareous, per- 

 forate, surface crossed by numerous continuous costae, 

 which may become lamellar and thickened near the 

 sutures. Aperture terminal, elliptical or reniform, fre- 

 quently interrupted by fusion with the columellar 

 spout, which is arched in cross section and may rarely 

 give the appearance of two teeth. Columellar process 

 well developed, spoutlike in shape, developed from the 

 early stage, each successive simple intercameral spout 

 with its concave side facing in the opposite direction to 

 that of the spout inimediately preceding, and each 

 apertural lip, except that of the final chamber, con- 

 nects to the extremities of two sections of spout, the 

 terminal end of the inferior one and the base of that in 

 the succeeding chamber situated diametrally opposite 

 in the circular opening and both having their convex 

 surface oriented toward the opening. 



Discussion: A study of numerous topotypes was 

 made. Acid-treated specimens show clearly the char- 

 acters of the "siphon" described by Plummer (1931) 

 and Stone (1946) and of the early stage. The early 

 stage is always biserial, even in megalospheric forms. 

 No specimen showed a triserial beginning. The biser- 

 ial stage is very short in the megalospheric forms (2 to 

 6 chambers), and more fully developed in microspheric 

 ones (as many as 10 chambers). 



A longitudinal acid-section shows (fig. 10) the in- 

 ternal aUgnment of the columellar process. The sec- 

 tion was purposely not completely axial, and the pre- 

 vious interpretations of the internal structure are cor- 

 rected as follows: The internal process is not a "tube" 

 as described by both Plummer and Stone, who gave 

 extremely small figures; it is an hemicylindrical sub- 

 vertical process (spout), joining from one opening to 

 another of two adjacent chambers. The spout always 

 lies with the convexity oriented toward the apertural 

 opening and is not continuous; there are single sections 

 for each chamber, and each opening, except that of 

 the last chamber, receives on one side the terminal 

 portion of one section of spout and on the other side 

 the beginning of the superjacent one. This alignment 

 is very regular and is shown in the figures. 



The position and the direction of the convexity of 

 the spout explains the secondary small opening ob- 

 served by Plummer. The aperture of the last chambers 

 receives only the end of one section of spout. In the 

 region of the termination of the spout the apertural lip 

 may be reduced or absent, and the section of the end 

 of the spout (which has the convexity facing the aper- 

 ture) may be secant and simulate a second small open- 

 ing. According to the different position of adherence 

 of the spout to the apertural lip, different shapes of 

 apertural outline (subcircular, reniform, irregular) may 



A relationship of Siphogenerinoides with triserial 

 genera must be excluded. The presence and the 

 nature of the columellar process, the biseriality of the 

 early stage, and the apertural features are the char- 

 acters important for its systematic placement. Accord- 

 ing to the present morphological revision, a close rela- 

 tion with Siphogenerina now appears probable. Only the 

 character of the columellar process seems still to distin- 

 guish Siphogenerinoides from Siphogenerina. Sigal (1952, 

 p. 219, fig. 80, p. 220, pi. 16, figs. 17a,b) states that 

 Siphogenerinoides (which he includes in the Uvigeri- 

 ninae, with triserial initial stage) has the columellar 

 process "external" to the apertm-e, instead of "internal" 

 as in Siphogenerina. A further investigation as to the 

 variability of the joining position of the columellar 

 process to the aperture in both Siphogenerina and 

 Siphogenerinoides is recommended. 



Genus Zeauvigerina Finlay, 1939 



Plate 34, Fioures 11, 12 



Zeauingerina Finlay, Trans. Proc. Roy. Soc. New Zealand, 

 vol. 68, p. 541, 1939. 



Type species: Zeauvigerina zelandica Finlay, 1939, 

 middle-upper Eocene, Danneverke area. New Zealand. 



Diagnosis: Test small, subcircular to elliptical in 

 cross section. Chambers biseriaUy arranged, minute 

 and depressed in the early stage, rather inflated in the 

 mature stage; sutures horizontal to oblique, with an 

 angle of up to 15 degrees from the horizontal. Final 

 chamber frequently less inflated than the penultimate, 

 flask-shaped, tending to become central and provided 

 with a neck, which is commonly almost as large as the 

 last chamber. Apertural margin proportionaUy thick, 

 circular or elliptical, internaUy provided with fine 

 tuberculate ridges, commonly reducing the aperture 

 to an elliptical opening. Wall calcareous, surface 

 fairly rough, rarely finely spinulate. 



Discussion: Only three paratypes were available in 

 the U. S. National Museum coflection, consequently 

 an analysis of the internal structure of the test was 

 practically impossible. Finlay based the separation of 

 this genus from Eouvigerina Cushman on the complete 

 biseriality of the new genus, compared to the "coiled" 

 first stage and the "triserial" arrangementof the mature 

 stage in Eouvigerina. The critical review made by 

 Loeblich (1951) recognized that neither coiled early 

 stage nor triseriality are present in Eouvigerina. Con- 

 sequently, Loeblich considered Zeauvigerina a synonym. 



The present investigation revealed the presence of a 

 toothplate in Eouvigerina. The same internal char- 

 acter may be present in Zeauvigerina also, but it is still 

 unrecognized; the three paratypes examined are in- 

 ternally filled with sand, and an investigation by 

 transmitted light was inconclusive. 



If aU external characters were identical to those of 

 Eouvigerina, the generic name of Finlay doubtless should 

 be invalidated, and the problem of the presence of the 

 toothplate set aside for the present, as we do not yet 

 know how widespread is this single character in the 



