ART. 22. CYCLOSTOMATOUS BRYOZOA CANU AND BASSLER. 97 



Structure. — Exteriorily many of the tubes are closed by a facette. 

 These are perforated by a circular aperture with peristome but 

 always closed by a pseudo-operculum. We have never seen a facetted 

 tube with an open aperture. This phenomenon is inexplicable in the 

 present state of the science. The other tubes have a large polygonal 

 opening. 



In transverse section the basal lamella appears as a straight or 

 undulated line. The tubes are polygonal and arranged symmetri- 

 cally on each sidje. In the periphery the expanded part of the tubes 

 has hollow vesicular walls. 



In longitudinal section the basal lamella is thick. The tubes are 

 short with triparietal gemmation. The inferior part presents a 

 variable number of diaphragms, sometimes close together. The ex- 

 panded portion of the tube shows vesicular walls and diaphragms 

 variable in position. The orifices l)eing arranged in quincunx, the 

 section is often tangential to the wall of the tube which appears 

 black in all of its concourse. 



We have not discovered the ovicell of this species, but all of its 

 features appear to favor its reference to this family. 



Occurrence. — Jurassic (Bathonian) : Luc and Ranville (Calva- 

 dos), France. 



Plesiotypes.—Canu collection and Cat. No. 68913, U.S.N.M. 



Genus HAPLOOECIA Gregory, 1896. 



1896. Haplooecia Gregory, Catalogue of fossil Bryozoa in the British Mu- 

 seum, Jurassic, p. 157. 



The characters of this genus are noted in the following description 

 of the genotype. 



Genotype. — Haplooecia straminea Phillips, 1829. Jurassic. 



HAPLOOECIA STRAMINEA Phillips, 1829. 



Plate 14, figs. 14, 15. 



1896. Haplooecia straminea Gregory, Catalogue of the fossil Bryozoa in the 

 British Museum, Jurassic p. 159, figs. 11, 12. 



We have not discovered the ovicell of this species, and our present 

 studies are based upon thin sections, which permit the reference of 

 the genus to the Ceriocavidae. In longitudinal section the tubes are 

 analogous to those of Ceriocava. They are long, cylindrical in their 

 rectilinear part, and much expanded in their recurved portion. Gem- 

 mation is peripheral, and the zoarial axis appears to be occupied by a 

 tube which branches at the bifurcations. The terminal walls are 

 hollow, but not vesicular, as in Ceriocava. In transverse sections the 

 tubes are polygonal, and those of the periphery alone have hollow 

 walls. 



