THE AEENIG AND LLANDEILO E0CKS OE ST. DAVID'S. 663 



species, to which the specific name recurvus might be given ; it is 

 here only regarded as a variety. It occurs associated with the 

 normal form in the quarry near Shelve Church before referred to 

 (vide p. 636). 



Log. Lower Arenig, Road Uchaf, Ramsey Island (both forms). 

 Middle Arenig, Whitesand Bay (normal form only). 



Dendeogeapttts peesctjlptus, Hopk., sp. nov. PI. XXXYI. 

 figs.4a-4cZ. 



Diffuse and irregular in form, frequently and somewhat regularly 

 branched ; branches robust, maintaining a width of about one 

 fortieth of an inch throughout, gently undulating, and diverging 

 only slightly from each other ; hydrothecse about 20 to the inch, 

 delicately chiselled or fluted longitudinally on all sides, expand- 

 ing slightly towards their distal ends, and curving so that their 

 apices project slightly beyond the general margin of the ventral 

 side of the branches, the dorsal side being here slightly indented, 

 giving the branches an articulated appearance. 



Of this beautifully sculptured species we have only a single spe- 

 cimen. Its length is about two inches, and its breadth an inch and 

 a half. It is in a much better state of preservation than any other 

 dendroid Graptolite we have found in the St. -David's rocks, Arenig 

 or Llandeilo ; and it owes its perfect preservation to its conversion 

 into iron pyrites, a small portion only being covered by the white 

 film which obscures the structure of almost every Graptolite we have 

 obtained from the Lower Arenig rocks. 



The only species to which Dendrograptus persculptus bears any 

 resemblance is Hall's D. striatus ; but the resemblance is only super- 

 ficial, as a comparison of the figures and descriptions of the two 

 species will show. 



Log. Lower Arenig, "Whitesand Bay. 



Dendeogeapttts aebtjscula, Hopk., sp. nov.. PI. XXXYI. figs. 5 a 

 &56. 



1873. Dendrograpsus arbuscida, Salter, MS., Catalogue Cambr. and 

 Silur. Poss. in Cambridge Museum, p. 21. 



About half an inch in length, very slightly branched, branches un- 

 dulating, extremely slender, scarcely diverging at all from each 

 other ; hydrothecse from 50 to 60 to the inch, cup-shaped in 

 form, twice as wide at their distal as at their proximal end, 

 their maximum width not exceeding one sixtieth of an inch, 

 by their rapid expansion giving the branches an articulated 

 appearance. 



This species was first discovered by Mr. Hicks some years ago in 

 the lower part of the Arenig rocks in Whitesand Bay, and the spe- 

 cimen in the Cambridge Museum, collected by him, was named 

 Dendrograjotus arbusGula by Mr. Salter ; but the species has not 

 until now been described or figured. All our specimens are pre- 



