. Bulletin - United States National Museum. Science. 376 BULLETIN 100, UNITED STATES NATIONAL MUSEUM apertural face; on the other face the zooecia are turned alternately to the right and to the left. Genotype.—Retepora elegans Reuss, 1847. Oligocene. The genotype is a very rare fossil. The structure appears to us to be rather removed from true Retepora to justify the employment of D'Orbigny's genus. We class it in the second group of Reteporidae (After Waters) awaiting more complete studies. It does not have vibices. Family ADEONIDAE Jullien, 1903 See Canu and Bassler, 1920 and 1923, for descr
. Bulletin - United States National Museum. Science. 376 BULLETIN 100, UNITED STATES NATIONAL MUSEUM apertural face; on the other face the zooecia are turned alternately to the right and to the left. Genotype.—Retepora elegans Reuss, 1847. Oligocene. The genotype is a very rare fossil. The structure appears to us to be rather removed from true Retepora to justify the employment of D'Orbigny's genus. We class it in the second group of Reteporidae (After Waters) awaiting more complete studies. It does not have vibices. Family ADEONIDAE Jullien, 1903 See Canu and Bassler, 1920 and 1923, for descrip- tion of this family and its genera. Genus ADEONA (Lamouroux, 1816) Levinsen, 1909 ADEONA POROSA, new species Plate 50, fig. 7 Description.—The zoarium encrusts nullipores. The zooecia are distinct, separated by a deep fur- row, large, elongated, elliptical, completely sur- rounded by a line of parietal dietellae; the frontal is convex and porous. The apertura is semiellip- tical, transverse and placed at the bottom of a short peristomie. The peristome is smooth, thick, nonsalient. The ascopore is large and placed in the middle of the frontal. The avicularium is located between the ascopore and the apertura; it is large, oblique, triangular, with the point directed upward. Measurements.—. Fig. 143. — Genus Sparsiporina D'Or- bigny, 1851. A, B. Sparsipo- rina elegans Reuss, 1848. A. Dorsal side with its characteris- tic appearance of the zooecia turned alter- nately to the right and to the left, X 25. B. Frontal side of a branch, X25, show- ing the recumbent ovicell. (After Waters, 1891.) . \Jia = mm. Zooecia Lz mm. mm. lz mm. Affinities.—In its dimensions, its aspect and its oblique avicularium, this species resembles Adeona plagiopora Busk, 1859, which Smitt, 1872, found in the Gulf of Mexico. It differs from it in its porous frontal and in the absence of tuberosities on the peristome. It has much resemblance to Adeona gris
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