96 



PROCEEDINGS OF THE NATTOISTAL MUSEUM. 



ture. Gemmation occurs on the basal lamella visible in the trans- 

 verse sections and on the superior edge of the zoarium. 



Genotype. — Granrmiecavaj {CeHopora) dumetosa Michelin, 184G. 

 Jurassic. 



GRAMMECAVA DUMETOSA Defrance. 1824. 



Plate 16, figs. 1-7. 



1824. Millepora dumetosa Defkance, Dictionnaire des sciences naturelles, 



vol. 31, p. 84 (not Lamouroux). 

 184G. Ceriopora diimetosa Michelin, Iconographie Zoophytologique, p. 245, 



pi. 57, fig. 7. 

 1854. Ncuropora defrancei Haime, Description des Bryozoaires fossiles de 



la formation Jurassique, M^nioires de la SociSte geologique de France, 



ser. 2, vol. 5, p. 215, pi. 10, fig. 7. 



Historical. — Gregory was in error when in 1896 he classed this 

 species with Ceriocava corymhosa Lamouroux, 1821, as the sections 



Fig. 24.— Graramecava dumetosa Defrance, 1824. 



A. Transverse section, X 16. The median lamella is undulated. 



B. Tangential section, X 16. 



(5. Longitudinal section, X 16, showing the basal (median) lamella, dia- 

 phragms in the tubes and the vesicular walls. 

 Jurassic (Bathonian) : Luc (Calvados), France. 



which we have prepared indicate a quite different structure. The 

 nature of the tubes is indeed the same, but triparietal gemmation 

 occurs on the basal lamella in the present species. 



