82 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.61. 



The oeciostome is terminal. The tubes are closed by a perforated 

 facette. 



The genera of this family here discussed are M eliceritites Roemer, 

 1840, and Cyclocites^ new genus. Numerous names applied to various 

 forms of growth have been given, but the structure of the genotype 

 of each must be restudied before they can be recognized. 



Genus MELICERITITES Roemer, 1840. 



1840. Melicerititcs Roemer, Die Versteineningeu des norddeutschen Krei- 

 degebirges, p. 18. 



The tubes are expanded at their recurved extremity. Their gem- 

 mation is dorsal around one or more cylindrical axial tubes with 

 regular peripheral gemmation. The orifice of the facettes is semi- 

 circular. 



Genotype. — M eliceritites (Cerlopora) gracilis Goldfuss, 1827. 



The genera created by D'Orbigny and now considered synonyms of 

 31 eliceritites, are based upon zoarial differences only, but nevertheless 

 it is still necessary to verify all of them by properly made thin sec- 

 tions. Most of the species of this genus exhibit special zooecia termed 

 eleocellaria whose forms are very useful in specific determinations. 



Very frequently the tubes are arranged in transverse rows. The 

 longitudinal sections then have a special aspect as the hollow tubes 

 appear to alternate with solid ones ; in reality the latter are formed 

 by the walls of the tubes placed regularly between two others. 



There are several sorts of tubes shown in the same section. At the 

 center the tubes are capillary, cylindrical, and may not have borne 

 polypides. They ramify more regularly than in Heteropora and re- 

 lated genera. Laterally the polypidian tubes are greatly expanded 

 and considerably broacler but much less in length ; they result from 

 the last ramifications of the small central tubes. This arrangement 

 of the tubes is not restricted to the Eleidae as it may be observed in 

 the Plagioeciidae {Filicea, Laterocea) and in the Ceriocavidae. The 

 section through an eleocellarium is identical with that through the 

 other tubes. The eleocellaria appear therefore to form merely ex- 

 ternal ornaments. 



The calcareous lamella which closes the tubes is not a mobile 

 operculum, as often thought, but it is identical with the lamella, 

 which closes the tubes of a large number of cyclostomatous bryozoa 

 when the polypide dies or becomes aborted. 



The discovery of the ovicell of the Eleidae was made by Canu in 

 1897,' when he figured this structure on two occasions.^ Levinson 



" Bryozoaiies du Turonien des Janieres, Bulletin SociCt^ Geologique France, ser. 3, 

 vol. 25, p. 150, pi. 5, flff. 10. 



■> Idem, pp. 750, 752, 753, pi. 22, figs. 1, 2, 3, 6. 



