92 PKOCEEDINGS OF THE NATIONAL, MUSEUM. vol.61. 



Occurrence. — Jurassic (Bathonian) : St. Aubin, Ranville, and 

 Langrune (Calvados), France. 



Plesiotypes.—Canu collection and Cat. No. 68941, U.S.N.M. 



Genus SPIROCLAUSA D'Orbigny, 1852. 



1852. Sinroclausa d'Orbigny, Pal^ontologie frangaise, Terrain CrStace, 

 p. 883. 



In the Paleontologie Francaise D'Orbigny has exactly limited all 

 of his genera, but they are not entirely concordant with the de- 

 scriptions in the Prodrome, because these later studies were more 

 complete, the material more numerous, and the publication was more 

 definite. We can not admit the changes made by Gregory in the 

 classification, and we preserve the genus Sfiroclausa as it is de- 

 fined in the Paleontologie Francaise. Gregory, 1899, has classified 

 the genus Spiroclausa in the same family as Terehellarla., but this 

 is impossible, for the ovicells arc quite different. 



The genotype is extremely curious on account of its spiral zoarium 

 in appearance, like that of a corkscrew. The ovicell is a smooth 

 sack, little salient, elongated, and located between the salient spirals. 

 It appears to us to have some analogy with that of the Leiosoeciidae, 

 although w^e believe the genus better placed in the Ceriocavidae at 

 present. 



The tubes are cylindrical with hollow walls. 



SPIROCLAUSA SPIRALIS Goldfnss, 1827. 

 Plate 14, fig. 9. 



1827. Ceriopora spiralis Goldfuss, Petrefacta Geriuaniae, Bryozoa, vol. 1, 

 p. 36, pi. 11, fig. 2. 



1852. Spiroclausa spiralis d'Orbigny, Paleontologie francaise, Terrain 

 Cretace, vol. 5, p. 883, pi. 764, figs. 1-5. 



1899. Zonopora spiralis Gregoey, Catalogue fossil bryozoa in British Mus- 

 eum. Cretaceous, vol. 1, p. 427 (Bibliography). 



Structure. — The ovicell is a convex sack, smooth, located between 

 two successive spires. The tubes of the salient spires are long in 

 longitudinal section. Between them and forming the concave spirals 

 the shorter dactylethrae are arranged; they grow by successive 

 ramifications most of the time. Sometimes, however, they are trans- 

 formed into mesopores — that is to say, into anterior and superior 

 ramifications of a single tube. 



It is probable that this unusual spiral mode of growth is the cause 

 of the modification in form of the ovicell. 



When worn the specimens offer slightly the aspect of Zonopora, 

 but the spires always remain regular. 



