238 MK. J. W. GRE&OB.Y ON THE 



Miinster, in Goldfuss, No. i, i. p. 102, pi. xxxvi. fig. 13], of which Eeuss [No. ii, 

 p. 291, pi. sxix. fig. 13] has given a good figure ; from this it is distinguished by the 

 form of the orifice, the absence of a ridge on the lower side of the aperture, and the 

 much greater coarseness of the maculae. Waters [No. 12, p. 13] includes the Crosara 

 species as a synonym of M. coriacea (Esper). The same characters separate it from 

 M. milnsteri (Reuss) [No. 6, p. 30, pi. x. fig. 2], which is very nearly allied to M. gracilis. 

 As in the new species some of the zooecia and the opesiulse are replaced by large 

 pores, while in others these are no larger than some of the maculae, it is evident 

 that Mr. Hincks is fully justified in refusing to regard the presence of these opesiulae 

 as an essential character of the genus. 



Genus Ontchocella, JuUien, 1881. 



Diagnosis. Microporidae with large vicarious avicularia scattered over the zocecia 

 [JuUien, No. r, p. 277]. 



Species 1. Ontchocella magnoaperta, n. sp. 



Diagnosis. Zoarinm encrusting, forming a large compact crust. 



Zocecia usually hexagonal, occasionally becoming rounded at the edges and oval 

 where they are less crowded. Apertures slightly clithridiate, very large, occupying 

 nearly the whole front of the cell ; the aperture is restricted by a small lamina at the 

 lower side of the zocecium. The margins of the zocecia are raised, plain, and non- 

 crenulate. 



Avicularia : large vicarious cells, long and tapering ; irregularly scattered over the 

 zoarium. 



Distribution. Brockenhurst Beds (Mid. Headon), Brockenhurst. 



Type. Brit. Mus. No. 49738. Edwards Coll. 



Figures. PI. XXX. fig. 7. Part of zoarium, X ^ diam., including one of the large 

 tapering vicarious avicularia. * 



Remarks. The subdivision of the great genus Membranipora to which Jullien [No. i, 

 p. 277] gave the name Onychocella appears to be based on more reliable characters 

 than most of the genera which that author has proposed, and it seems to be now gener- 

 ally accepted [see Waters, No. 1 2, pp. 8, 9], The nature of the avicularian cells of 

 this new species shows that it belongs to this group. Its nearest ally is 0. angu- 

 losa (Reuss) [No. i, p. 93, pi. xi. fig. 10], from which it difl'ers in the much 

 smaller size of the aperture in that species. If, as Waters suggests, Shagasostoma 

 hexagonum, Kosch. [No. i. p. 30, pi. v. figs. 5-7], is only a synonym of 0. angulosa, it 

 will be unnecessary to compare them further ; but if, as appears probable, it is a 

 distinct species, the structure of the aperture will clearly distinguish it from the 

 Brockenhurst form. 



