64 W. M. Ilutchings — Clays, Slates, and Contact- Metamorphism. 



Distribution : Calcaire ^ polypiers (Bathonian.) Eanville, 

 Normandy, France. 



Type : Brit. Mus. D 181. 



Affinities. — The closest allies of OnycJiocella hathonica are four 

 species from the Cretaceous, which have been described under other 

 generic names. It is unfortunate that there is some doubt about its 

 nearest ally, a Maestrichtien species, described by Hagenow ; in his 

 monograph he has given two figures^ which he assigns to the 

 species Cellepora (Discopora) Tconinckiana ; but the structure of the 

 aperture is so different in the two, that I feel bound to assign them 

 to different species : in his first figure the aperture is mucronate 

 and is small ; in the second (fig. 11) the aperture is elliptic, with 

 the longer axis longitudinal, the lower mai'gin is entire, the aperture 

 occupies twice as large an area as in the former, and the avicularia 

 are much larger. I therefore make Hagenow's second figure 

 (fig. 11) into a new species under the name of Onchyocella hagenowi. 

 This is the nearest ally of 0. hathonica, but it differs in the larger 

 size of both the avicularian and zooecial apertures. 



Onycliocella piriformis (Goldf.)^ is another ally, but has a lower 

 zooecial aperture, while the avicularian aperture is larger and the 

 front wall occurs only above and not on both sides of this. 

 0. santonensis (D'Orb.)^ has a smaller mouth and longer avicularia; 

 0. solea (Novak)* a semi-elliptical aperture with a mucronate lower 

 margin. 



The result, therefore, of the present communication is the first 

 description of Bryozoa of the order Cheilostomata in the Jurassic ; 

 the species described belong to the two families of the Membrani- . 

 poridcB and Microporidce ; but representatives in this age of the 

 Cellariidce, Smittidce, and other families are also included in the 

 British Museum Collection. 



in. — Notes on the Composition of Clays, Slates, etc., and 

 ON Some Points in their Contact-Metamorphism. 

 By W. Maynard Hutchings, Esq. 

 {Concluded from the January Nuinher, p. 45.) 



AFTER this substance has been well observed in good 

 occurrences, it is always recognized at once, even as 

 isolated small patches in a slide. It has a very characteristic 

 appearance among the other constituents. It is marked off, for 

 instance, by its special refraction from anything else that occurs in 

 these rocks, and has other characteristics not to be missed when 

 once observed, but not very easy to exactly describe. As soon as 

 it ceases to be quite inert in polarized light, as soon as the 

 speckly polarization sets in, it has also a more or less granular 



1 Hagenow, op. cit. p. 95, pi. si. figs. 10 and 11. 



2 Eschara piriformis, Goldfuss, op. cit.^. 24, pi. viii. fig. 10; Hagenow, op. cit. 

 p. 75, pi. ix. fig. 6 ; pi. xi. fig. 6. 



3 Eschara santonensis, D'Orbigny, op. cit. p. 109, pi. 603, figs. 1-3; pi. 673, 

 fig. 4. 



* Bijlustra solea, Novak, op. cit. pp. 94-95, pi. iii. figs. 12-16. 



