150 



UNITED STATES NATIONAL MUSEXXM BXTLLETIN 215 



smaller Foraminifera, nor what is its systematic im- 

 portance. But in Zeauvigerina (at least in the para- 

 types studied) the chambers are strongly compressed, 

 with almost horizontal sutures, instead of having the 

 rather loosely appressed chambers of Eouvigerina; the 

 last chamber is smaller in size than the penultimate in 

 Zeauvigerina, the neck is considerably larger and the 

 apertural cavity more reduced than in Eouvigerina. 

 Consequently, these features have led the writer to 

 maintain, although with many doubts, the name 

 Zeauvigerina, untU a complete structural, morpholog- 

 ical, and, if possible, statistical investigation of abun- 

 dant material of both "genera" is made, showing 

 transitional forms between the two populations. 



Genus Trachelinella Montanaro Gallitelli, 1956 



Plate 34, Figure 13 



Trachelinella Montanaro Gallitelli, Contr. Cushman Found. 



Foram. Res., vol. 7, p. 38, pi. 7, figs. 8-10, 1956. 

 Trakelina Montanaro Gallitelli, Mem. Accad. Sci. Lett. 



Arti Modena, ser. 5, vol. 13, p. 5 (nomen nudum), 1955. 



Type species: BoUvina watersi Cushman, 1927, Upper 

 Cretaceous Navarro (Maestrichtian), Core A-D-1 (Sun 

 Oil Co.), from east of Richlands, Navarro County, 

 Texas. 



Diagnosis: Test elongate, flaring gradually, com- 

 monly twisted as much as 90 degrees, thickest in 

 median line; periphery subacute, generally carinate, 

 or more rarely serrate. First chamber with a basal 

 spine and rarely two opposing median costae; adult 

 chambers strongly arched. Sutures narrow, arched, 

 deep. Wall calcareous, finely perforate, smooth. 

 Sculpture well developed, with prominent, rough, 

 somewhat spinose carinae, aligned along the major 

 extension and inflation of the chambers and con- 

 sequently strongly arched, commonly fused at the 

 lateral margins, which become carinate or serrate. 

 Aperture terminal, round or slightly elliptical, with a 

 short neck and a lip. No apertural internal teeth 

 visible, at a magnification of more than 200 diameters. 



Discussion: This genus is very abundant in the 

 Upper Navarro Kemp clay. The holotype of "BolimMi" 

 watersi Cushman is a specimen with a broken apertural 

 neck, giving an erroneous Bolivina-hke appearance. A 

 short apertural neck is visible at high magnification on 

 one of the two broad faces of this specimen. 



This genus differs from BoUvina in the presence of a 

 well developed neck which may relate it to the 

 Eouvigerininae. The oblique axis, the short neck of 

 the last chamber, and the biserial arrangement of the 

 chambers also suggest a relationship with Bolivinitella, 

 although the latter genus has a peculiar rectangular 

 section, concave broader faces, and four vertical 

 lamellar costae, features not characteristic of Trache- 

 linella. 



Additional specimens of the type species were recently 

 figured by the writer, hence are not here refigured. 



Genus Bolivinitella Marie, 1941 



Plate 34, Figures 14^17 



Bolivinitella Marie, 1941, Mem. Mus. Hist. Nat., new ser., 

 vol. 12, p. 189. 



Type species: Bolivinita eleyi Cushman, 1927, Upper 

 Cretaceous Brownstown marl, 8.1 imles west of Arka- 

 delphia, Clark County, Arkansas. 



Diagnosis: Test elongate, biserial throughout, 

 rectangular in section and compressed. Broader sides 

 flat or concave, chambers reniform, strongly over- 

 lapping and arched in the mature stage, tending to 

 become uniserial. Last chamber strongly compressed 

 at the upper portion. Sutures limbate, strongly 

 arched on the broad sides and fused at the four angles 

 to form four longitudinal carinae. Aperture terminal, 

 linear or elliptical, may have a lip, the apertural cavity 

 finely tuberculate. 



Discussion: Hofker's peculiar conclusions con- 

 cerning this genus are not supported by sufficient 

 observation. He invalidated the present generic name 

 and placed Bolivinitella with Siphogaudryina, which 

 has, however, an arenaceous test and a triserial early 

 stage. As the test of Bolivinitella is calcareous and 

 soluble in dilute hydrochloric acid, a diagnosis of the 

 so-called secondary material (granules) by optical and 

 X-ray methods is required. When partially acid- 

 treated the test shows a transparent shell material at 

 high magnification. 



Dissections by acid and observations of the genera- 

 tion B of Hofker did not show any triserial early ar- 

 rangement of the chambers in any of the numerous 

 specimens in the National Museum collections. How- 

 ever, a strongly tuberculate or more rarely costate 

 ornamentation at the beginning of the test is very 

 frequent. 



The absence of a toothplate is substantiated, not 

 unexpectedly, because of the extremely thin antero- 

 dorsal section of the final portion of the last chamber. 

 If a toothplate is present in the young stage (because 

 of the smallness of the specimens, this could not be 

 demonstrated at X 216 magnification or by acid- 

 treatment) it must be obviously absent in the apertural 

 extension of the chamber. The aperture is not exactly 

 as described by Hofker, but is more frequently linear 

 and occasionally elHptical, and provided with a lip. 

 In the best preserved specimens the lip shows internally 

 a relatively well developed granulation which may 

 obliterate the aperture and perhaps even cause it to 

 become cribrate. 



For these reasons the consideration of Bolivinitella as 

 a synonjrm of Siphogaudryina is discounted, and the 

 genus is here held to be valid. The position and feature 

 of the aperture, and the shape of the chamber are 

 constant and distinctive generic characters, despite the 

 absence of the toothplate. 



