THE ARENIG AND LLANDEILO ROCKS OF ST. DAVID'S. 671 



Figs. 3a-3d. Didymograptus furcillatus, Lapw. From Abereiddy Bay : Lower 

 Llandeilo {coll. J. H.). 



4 a-4 c. Didymograptus indentus, var. nanus, Lapw. From Abereiddy Bay : 



Lower Llandeilo (coll. H. H. 3f J. H.). 



5 a & 5 b. Dicellograptus moffatensis, Carr., sp., nat. size. From Abereiddy 



Bay : Middle Llandeilo (coll. J. H.). 



6 a & 6 b. Diplograptus tricornis, Carr., nat. size. From Abereiddy Bay : 



Lower Llandeilo (coll. H. H.). 

 7a-7g. Diplograptus foliaceus, Murch., sp. From Abereiddy Bay : Lower 



Llandeilo (coll. H. H. $ J. H.). 

 8 a-8 e. Climacograptus ccslatus, Lapw. From Abereiddy Bay : Lower 



Llandeilo (coll. J. H.). 



Plate XXXVI. 



Illustrative of the Arenig Cladophora described by Mr. Hopkinson. 



Figs. 1 a & 1 b. Ptilograptus Hichsii, Hopk. 1 a, natural size ; 1 b, part of the 

 same, magnified 5 diameters. From Boad Uchaf, Bamsey Island : 

 Lower Arenig (coll. H H). 



2 a & 2 b. Ptilograptus cristula, Hopk. 2 a, nat. size. ; 2 b, part of the 



same, magn. 5. From Road Uchaf : Lower Arenig (coll. J. H). 



3 a-3 d. Dendrograptus flexuosus, Hall. 3 a, normal form, nat. size. From 



Boad Uchaf : Lower Arenig (coll. J. W. K.). 3 b, var. recurvus, Hopk., 

 nat. size. 3c, 3d, young individuals, nat. size. From Boad Uchaf : 

 Lower Arenig (coll. J. H.). 



4:a-4:d. Dendrograptus persculptus, Hopk. A. a, nat. size; 45, 4c, 4:d, 

 portions of the same, showing the various appearances presented by 

 the branches, magn. 5. From the creek north of Trwyn-hyrddyn, 

 Whitesand Bay : Lower Arenig (coll. H. H.). 



5a&5b. Dendrograptus arbuscula, Hopk. 5a, nat. size. From White- 

 sand Bay: Lower Arenig (coll. H. H.). 5 b, nat. size. From Boad 

 Uchaf, Bamsey Island : Lower Arenig (coll. H. H.). 



QakQb. Dendrograptus divergens, Hall. 6a, nat. size; Qb, part of the 

 same, magn. 5. From Boad Uchaf: Lower Arenig (coll. J, H.). 



7 a & 7 b. Dendrograptus diffusus, Hall. 7 a, nat. size ; 7 b, part of the 



same, magn. 5. From Boad Uchaf : Lower Arenig (coll. J. H.). 

 8a&8b. Callograptus radiatus, Hopk. 8a, nat. size. From the creek 

 north of Trwyn-hyrddyn, Whitesand Bay : Lower Arenig (coll. J. H.). 

 8 b, a young individual, nat. size. From Road Uchaf, Bamsey Island: 

 Lower Arenig (coll. D. H.). 



9. Callograptus elegans, Hall, nat. size. From the slate-quarry, White- 



sand Bay : Middle Arenig (coll. J. H.). 



10. Callograptus Salteri, Hall, nat size. From Whitesand Bay (slate- 

 quarry) : Middle Arenig (coll. J. H.). 



11 a & 11 b. Dictyograptus (Desmograptus) cancellatus, Hopk. 11a. nat. 

 size ; 11 b, part of the same, magn. 5. From the creek north of Trwyn- 

 hyrddyn, Whitesand Bay : Lower Arenig (coll. J. H.). 



12. Dictyograptus irregularis, Hall, nat. size. From Whitesand Bay (near 



the slate-quarry) : Middle Arenig (coll. J.H.). 



13. Dictyograptus Homfrayi, Hopk., nat. size. From Road Uchaf, Ramsey 



Island : Lower Arenig (coll. D. H.). 



Plate XXXVII. 



Illustrative of the Llandeilo Cladophora described by Mr. Hopkinson. 



Figs. 1 a & 1 b. Ptilograptus acutus, Hopk. 1 a, natural size ; 1 b, portions of 

 three branches of the same in their natural position, magnified 5 

 diameters. From Abereiddy Bay : Lower Llandeilo (coll. J. K). 

 2 a & 2 b. Dendrograptus Ramsayi, Hopk. 2 a, nat. size ; 2 b, part of a 

 branch of the same, magn. 5. From Abereiddy Bay ; Lower Llandeilo 

 (coll. H. H.). 

 Q. J. G. S. No. 124. 2 y 



