408 



BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



Genus CHEILONELLA Koschinsky, 1885 



The zooecia are very large; the frontal is smooth and ornamented 

 with very small marginal pores. The peristomie is free, salient; the 

 peristome is orbicular with a proximal denticle. The zoarium is uni- 

 serial. Aperture, ovicell? 



Genotype. — Cheilonella gigas Koschinsky, 1885. Eocene (Lutetian). 



Psilopsella and Cheilonella with their giant cells do not belong to 

 the family of Phylactellidae but as they are incompletely described 

 we are not able to classify them correctly. 



Family CREPIDACANTHIDAE Levinsen, 

 1909 



In 1920 we classed Crepidacantha Levin- 

 sen, 1909, in the family Phylactellidae, in 

 company with Mastigophora, because of the 

 recumbent nature of the ovicell. Now that 

 we have been able to study three species of 

 Crepidacantha, we believe it necessary to 

 maintain Levinsen's family. In reality the 

 large larva of the Phylactellidae, measuring 

 according to Waters 0.30 to 0.35 mm. in 

 length, could not possibly develop in the 

 ovicells of Crepidacantha and Mastigophora 

 that measure only from 0.15 to 0.25 mm. in 

 diameter. A different larva corresponds 

 always to a different family. On the other 

 hand, inspection of the figures alone reveal 

 close analogies between the two genera cited. 

 The three known genera of this family are, 

 then, Crepidacantha Levinsen, 1909, Mastigo- 

 phora Hincks, 1880, and Scliizobathy sella 

 Canu and Bassler, 1917. 



Genus CREPIDACANTHA Levinsen, 1909 



Fig. 159. — GenusCheilonella 

 Koschinsky, 1885 



Cheilonella gigas Koschin- 

 sky, 1885. Zooecia, X25. 

 Lutetian of Bavaria. (After 

 Koschinsky.) 



The ovicell is recumbent and closed by 

 the operculum. The frontal is a tremocyst with very small pores. 

 The aperture shows a semicircular anter and a poster shorter and 

 wider, separated by two salient cardelles. Long setiform spines 

 corresponding to the parietal dietellae surround the zooecia. 



Genotype. — Crepidacantha (Flustra) poissonni Savigny Audouin, 

 1826. Recent. 



Historical. — The synonymy of the genotype, Flustra poissonni 

 Savigny Audouin, 1826, is very confused. Several very distinct 

 species can be separated. 



