566 ME. £. E. L. DIXON AND DR. A. VATJGHAN ON [iSToV. I9II, 



EXPLANATION OF PLATES XXXVIII-XLI. 



Plate XXXVIII. 



Fig. 1. ' Pitted ' limestone in D l , Tor-gro (North- Western Gower). A steeply- 

 dipping, weathered bedding-plane. The bag near the right lower 

 corner affords a scale. The limestone is a pseudobreccia, and shows 

 the usual rough surface. (See pp. 490 & 499.) 



Fig. 2. Undolomitized pseudobreccia inD,, slightly weathered, Tor-gro. The 

 dark angular ' fragments : are well defined. Dolomite is absent, from 

 both ' fragments ' and ' ground-mass ' ; the amount of argillaceous 

 impurity is very slight. (See pp. 507 et seqq.) 



Plate XXXIX. 



Partly dolomitized pseudobreccia in L\, Port Eynon (South-Western Grower). 

 Microscope-section X 8 diameters. The dense material is unaltered 

 'ground-mass'; the less cloudy, much more foramini feral areas, at the 

 top, bottom, and left, are the recrystallized 'fragments'; the rhombo- 

 hedral crystals, many with a diagonal cross, in the ' ground-mass ' are 

 dolomite. (See pp. 507 et seqq.) 



Plate XL. 



Upper Avonian corals from the Cyatliaxonia Phase (Bv 3 ) of Oystermouth, 

 Gower (together with certain forms for comparison). 



Figs. 1 a-\ e. Zaphrentis oystcrmouthends, sp. nov. (p. 553). Fig. 1 a, ex- 

 ternal and calicular view, natural size. Base of D 2 _ 3 , North Colts 

 Hill Quarry. Collected by Mr. Underbill. (For septal plan and 

 curvature of tabulae in this specimen, see text-figs. pp. 554 & 555.) 

 Figs. 16-1 e. All from J ) 2 _ 3 , Oystermouth Quarry ('Black Lias'). 

 Fig. 1ft, a very young form, X 2^. Fig. 1 e, intermediate stage 

 of tbe same specimen, X I5. Fig. 1 d, intermediate stage of 

 another specimen showing differences due to the position of the 

 section with regard to new septa. Fig. 1 e, adult stage, X 1$. 



Fig. 2 (for comparison). Zaphrentis enniskiUeni Ed. & H. (p. 554). Natural 

 size. The holotype of the species. \Olim Coll. Geol. Soc, R. 5460. — 

 Now in the Museum of Practical Geology.] Lough Gill (Co. Sligo). 



Figs. 1 3a-3 c. Caninia aff. cornucopia Mich., mut. D 2 _ 3 (p. 555). Three 

 sections from the same specimen, D _ 3 of Oystermouth Quarry. 

 Fig. 3a, young stage, X 2 - 7. Fig. 3 b, intermediate stage, X 14> 

 Fig. 3 c, adult stage, X I i- 



Fig. 1 4 (for comparison). Caninia cornucopia Mich., Carruthers (p. 556). 

 Section, X 1£. Stackpole Quay, Pembroke. Horizon y. 



Fig. 5. Caninia (?) sp. (p. 556). Natural size. Base of D 2 _ 3 , North Colts 

 Hill Quarry. Collected by Mr. Underbill. 



Figs. 6 a & 6b. Amplexus sip. (p. 557), D 2 _ 3 of Oystermouth Quarry. Fig. Qa, 

 external view, X l?- Fig. 6b, section, X 1"2, 



Fig. 7. Dibunophyllum Vaughan (to right) and Dibunophyllum aff. ty 

 Vaughan (to left), slightly reduced ( X - 94). L T of Port Eynon 

 (p. 558). 



Plate XLI. 



Upper Avonian bracbiopods from the Cyathaxonia Phase (D 2 _ 3 ) of Oystermouth 

 and Bishopston, Gower (together with certain forms for comparison). 



Figs, la & lb. Productus sulcatus Sow, (p. 559). Natural size. D 3 _ 3 of 

 Oystermouth Quarry. Fig. 1 a, pedicle-valve, rostral view. Fig. 1 b, 

 pedicle-valve, marginal view. 



1 In figs. 3 b and 3 c the fossula lies to the right of tbe plane of symmetry 

 for the external surface ; figs. 3 a and 4, in which the fossula lies in the plane 

 of symmetry, have been set obliquely so as to facilitate comparison. 



