Neithea roemeri (Hill, 1889)
HILL, R. T. 1889. Paleontology of the Cretaceous formations of Texas. Part I. University of Texas, School of Geology, 7 p. (unnumbered), pIs. 1-3. [p. [5], pl. 1]
1889 Pecten (Vola ?) roemeri Hill, 1889
«Pecten (Neithea) roemeri HlLL 1889, 5 3, pl. I. SHATTUCK 1903, 86, 15, pls. II- IV; pl. V, fig. 1. KNIKER 1919, 62, 43, pl. IX, figs. 1-3; pl. X, fig. 1.
Large species, outline suboctahedral, right valve elevated, ears prominent with subequal, radial costellae; posterior ear larger. Right valve with 6 irregular, unequal, prominent radial folds; the folds and depressions contain irregular, unequal costae and costellae. The species is larger, more elevated and more ornately ribbed than P. duplicicosta.
Upper Buda: Austin (type locality).»
ADKINS, W. S. 1928. Handbook of Texas Cretaceous fossils. Bulletin of the University of Texas, 2838: 385 p., pls. 1-37. [p. 126]
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«Description. — Shell large, thick, compressed, asymmetrical, inequivalve, length only sligthly greater than height; outline suboctahedral. The subsemicircular, scalloped ventral margin shows six projections formed by the extensions of the folds. At the base, the convexities of one valve fit into the concavities of the other. Ears prominent, posterior larger than anterior; hinge line long and straight, and equal to about three-fourths the length of the shell.
Right valve convex, somewhat larger than the left, beak prominent and elevated. The surface is decorated with six unequal radiating folds that are distributed in an irregular manner and ornamented with costae and costellae of different sizes and shapes. On first sight, it appears as if there is no regularity whatever about the arrangement, but upon closer investigation, a system can be made out. Each fold has a prominent rib at the summit and others of different sizes on the slopes. The summit costae are practically equal, and similar in shape. Between the several folds are found narrow depressions scarcely wider than those between the prominent ribs. The fourth fold, although not the largest, is most pronounced, and projects farther out than the others at the ventral margin. It is also the highest one and the center of symmetry. Its summit is formed by a narrow rib rounded on top. On each slope are two small ribs varying somewhat in size, the lower ones tending to be more prominent. Across the intercostal depression posterior to this fold a broad flat-topped rib is found near the summit of the fifth fold, and on the summit there is a prominent costa. On the posterior slope are two smaller ribs, one of them being almost in the interfold furrow. On the anterior slope of the sixth fold is a small rib practically equal to its neighbor across the furrow. On the posterior slope are found four ribs, the first and last being insignificant, and the second more prominent than the third. The third fold is broader than any of the others. Its summit also shows a prominent, narrow, rounded rib, which has a fine radial plication on the anterior side. The ribs on the posterior slope correspond in shape and arrangement to those on the anterior slope of the fifth fold. On the anterior slope are found two prominent unequal ribs. The larger rib is similar to the corresponding one on the other slope of this fold and is nearer the summit. The second fold has a conspicuous rib near the base on either side, and a smaller one higher up on the anterior slope. There is a prominent costa on the posterior slope of the first fold, being even larger than the one forming the summit. On the slope adjoining the ear there are three small ribs, more or less alike. In young specimens the folds are relatively higher than in the more mature forms. The conspicuous ears are ornamented with prominent radiating and practically uniform costae. Left valve somewhat less convex than the right, beak depressed. As in the right valve, there are six folds. But as the ribs alternate with those of the right valve, there is a furrow on the summit of each fold. Most furrows tend to be wider than the ribs, incontrast to the relation on the right valve. On the anterior slope of the first fold there are three rather conspicuous ribs. There is a prominent rib posterior to the summit furrow, which is followed by a depression. On the anterior slope of the next fold, are found two well developed ribs. There is a smaller rib just beyond the summit and leaning against a very broad sloping costa. In the valley between this fold and the next lies a narrow, sharp rib. On the third fold two very prominent ribs enclose the summit furrow. On the fourth fold is found a high, narrow rib, followed by a broad, low one, which is separated from the former by a deep rounded depression. A deep narrow depression follows and, adjoining it, there are two medium sized costae separated by a very narrow furrow. The ornamentation of the posterior slope corresponds to that on the anterior. Between this fold and the next occurrs the broadest depression. The fifth fold consists of merely a distinct rib on either side of the summit furrow. This fold and the next are separated by a deep rounded furrow. On the anterior slope of the sixth fold is found a small, rounded rib and then a broad one adjoining the summit depression. On the posterior slope the ribs merge into those of the posterior ear. The ears are marked as on the right valve. On some specimens additional fine ribs have been noticed in some of the depressions. The posterior ear extends almost from the end of the projection of the posterior fold in a gentle curve to the end of the long hinge line. The anterior ear is smaller and is separated from the body of the shell by a deep groove. Further ornamentation consists of fine concentric striae, which are always parallel to the serrate margin, passing from the body of the shell to the ears. Growth ridges are also evident Remarks: — This species attains great size, the largest specimens collected having a height of 120 mm. and a length of 130 mm
Affinities.— This form groups with N. fleuriausiana (d'Orb.) and N. lapparenti (Chof.). N. roemeri differs from d'Orbigny's species in having the folds more unequal in every respect, in having fewer ribs and these very dissimilar, and inhaving broad furrows. The hinge line and the ears also are different. The Texas species has the former longer than and the latter more unequal than N. fleuriausiana. As has been mentioned in the description, the posterior ear of the right valve of N. roemeri extends almost to the projection of the posterior fold. Furthermore, the shell of N. roemeri is more asymmetrical and shows a different relation between the valves. In N. fleuriausiana the left valve is only slightly convex, whereas in the American species both valves are inflated, there being only a slight difference in the convexity.
This form is not so long in proportion as N. lapparenti and its valves are evidently more convex than those of the latter species. Moreover, the shape and distribution of the ribs is entirely different in the two species. Number of specimens: 22
Occurrence: Upper division of the Buda Limestone, Austin, Texas.»
KNIKER, H. T. 1919. Comanchean and Cretaceous Pectinidae of Texas. Bulletin of the University of Texas, 1817: 1-56, pls. 1-10. [p. 43-46]
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Neithea roemeri (Hill); H. T. Kniker, 1919, Comanchean and Cretaceous Pectinidae of Texas, plate 9, figures 1-3; plate 10, figure 1.
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«Dimensions.— Length, 15 cm.; breadth, 14 cm.
Description.— Shell large, compressed, thick; margin scalloped, concavities of one valve receiving the convexities of the other; suboctahedral; equilateral, unequivalved; right valve subglobose, left valve slightly convex; hinge line straight, two- thirds length of shell, medial, symmetrical, reflected toward left valve; umbos opposite, medial; that of the. right valve prominent, that of the left depressed; ears equal, produced, conspicuous, decorated with radiating costse. Surface decorations consist of six major radiating ribs, including between them groups of two or three minor costre. In the region of the wings the costse are of uniform strength. Concentric undulations are also prominent and lines of growth well marked. This Vola is very abundant in the Buda limestone, and suggested the name Vola limestone, by .which this formation was originally known. Mr. Hill, in discussing the Buda ("Shoal Creek") limestone in an early paper, (a) referred to this form as Vola quinquecostata Sow. Locality.— Shoal Creek, Austin, Tex.; Onion Creek, Buda, Tex. This form has never been reported from any other formation. Collections.— Johns Hopkins University; (b) & United States National Museum.» (a) Events in North American Cretaceous history, etc.: Am. Jour. Sci., April, 1889, 3d series, Vol. XXXVII, p. 290.
(b) Concerning the specimens described in this paper, it may here be said that Mr. Hill collected those in possession of the Johns Hopkins University, while those in possession of the United States National Museum were in great measure collected by the writer for the United States Geological Survey. SHATTUCK, G. B. 1903. The Mollusca of the Buda Limestone. Bulletin of the United States Geological Survey, 205: 9-35, pls. 1-25. [p. 15]
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Pecten roemeri (Hill); G. B. Shattuck, 1903, The Mollusca of the Buda Limestone, plates 2-4; plate 5, figure 1.
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«P. (VOLA) FLEURIAUSIANA D'Orb. var ROEMERI, Hill 5, 1889. V. Characteristic fossil of Shoal creek (Vola) limestone.»
HILL, R. T. 1889. Check list of the invertebrate fossils from the Cretaceous formations of Texas. University of Texas, School of Geology, 16 p. [p. 16]
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