126 MEMBRANIPORID^. 



« 



surface glistens when dried. The cells are arranged with 

 extreme regularity, and form a pretty and distinct lace- 

 work pattern on the frond. The structure is eminently 

 simple; spines, avicularia, and probably ooecia, are all 

 wanting. Grant describes the development of the ovum, 

 which is of a light-yellow colour, and its escape from the 

 cell itself into the water. 



Family VIII. — Memhraniporidae. 



Celleporid^e (part.), Johnston, Brit. Zooph. 

 Membraniporid^ (part.), Busk, B.M. Cat. 

 Fltjstrellarid.e (part.), D'Orbigny, Pal. Fran9. T. Cret. 

 EscnARiD,E (part.), id. ibid. 

 Escharellinid^ (part.), id. ibid. 

 Flustrellid-e (part.), id. ibid. 

 Flustrinid^ (part.), id. ibid. 

 Electrinid^e (part.), id. ibid. 

 Membraniporid.e, Smitt, Krit. Forteckn. 



ZoARiUM calcareous or memhrano-calcareous, incrusting 

 {so far as British species are concerned) *. Zocecia 

 forming an irregular continuous expansion, or in linear 

 series, ivith raised margins, and more or less mem- 

 branaceous in front. 



This family represents an earlier stage of zocecial 

 development, as compared with the two following. The 

 calcification of the cell is always more or less imper- 

 fect ; and in a large proportion of cases the whole of the 

 front is merely closed in by a membrane, a condition 

 which we meet with in the immature cells of the old 

 Lepralian group. 



* There are fossil and other forms with an erect habit of growth, which 

 from the structure of their zocecia, shoidd probably be included in this 

 family. 



