MEMBRANIPORIDtE. 35 



perhaps be a very decisive character, one of more importance exists in the presence in 

 M. (C) hippocrepis, of large, scattered, lanceolate avicularia among the cells, none of 

 which are visible in the figure of M. bidens, nor in the Crag specimens. 



11. M. ANDEGAVENSis, Michelin. PI. 11, fig. 5. 



Areis elongatis, supra arcuatis, lateribus subparallehs ; cellulis clausis, lamina depressa, 

 glabra, poro singulari medium supra utrinque perforata; orificio semilunari, elevato, 

 margine simplici ; ovicellulis raagnis, conspicuis. 



Area elongated, sides nearly parallel, rounded above ; surface of cell concave, smooth, 

 with a single pore on each side above the middle ; ridges simple, smooth ; orifice sub- 

 crescentic, raised ; peristome simple ; ovicell large, conspicuous. 



EscHAHA Andegavensis, Mich., Icon. Zoophyt., p. 329, pi. Ixxviii, fig. 11. 

 Habitat. — C. Crag, on shell, S. W. Doue, &c., Michelin. 



12. M. EissuRATA {n. sp.)"^ 



Area oblonga supra arcuata, infra truncata; septis tenuibus, simplicibus, glabris. 

 Orificio magno transverso, labro inferiori subrecto ; lamina utrinque fissuram longam 

 curvatam ostendente. 



Area oblong, arched above, truncate below ; ridges narrow, simple, smooth ; mouth 

 large, arched above, lower lip nearly straight, or raised in the middle; a long curved 

 fissure on each side of the front of the cell. 



Habitat. — C. Crag, on Eschara monilifera. 



A very well marked species, distinguishable at once by the elongated curved fissure 

 on each side of the front of the cell. The septa between the cells are thin and very 

 regularly arranged, and the calcareous lamina forming the front of the cell appears to be 

 extremely delicate and fragile, so that the specific characters are only here and there 

 apparent, even in a large patch. The sjiecies seems to be parasitic upon other Polyzoa, 

 and when the front of the cells is entirely destroyed may be distinguished by the large 

 size of the empty spaces left, the comparative thinness of their walls, and the absence of 

 intercellular avicularia. 



13. M. ocKANi, D'Orbigny. PI. Ill, fig. 8. 



Polyzoario effuso, irregulari ; cellularum areis pyriformibus, superne depressis, parte 

 depressa linea elevata circumscripta, utrinque poro lunato signata; orificio suborbiculari, 



' The figure of this species has been accidentally omitted. 



