Distribution of the Rhabdophora. 339 



amid the volcanic rocks of the Gelli Hills near Builth. In 

 the dark Llandeilo shales of Pwllacca near Llandeilo I have 

 seen the smaller varieties of Didymograptus Murchisoni in 

 myriads, together with Diplograptus foliaceus, Murch., Cli- 

 macograptus ccelatus, Lapw., and indeterminable forms of 

 Didymograptus. Didymograptus Murchisoni, Beck, is quite 

 as abundant in the black shales below the Limestone of 

 Llandewi Felfiy near Whitland, associated with Didymo- 

 graptus Nicholsoni, Lapw., Goniograptus, sp., Climacogr aphis 

 confertus, Lapw., DipAograptus tricornis, &c. The forms 

 recognized by Mr. Hopkinson and myself* in the Lower 

 Llandeilo zone of Abereiddy Bay include 



Didymograptus euodus, Lapw. Diplograptus foliaceus, Murch. 



indentatus, Hall. tricornis, Can: 



Murchisoni, Beck. Dicellograptus rnoffatensis ?, Carr. 



and some others. 



In the Middle Llandeilo of Abereiddy Bay are found 

 Dicellograptus, Diplograptus foliaceus, Murch., and D. tri- 

 cornis, Carr. In the corresponding strata of Builth Road 

 and Wellfield, Radnorshire, I have detected 



Dicellograptus patulosus, Lapw. Diplograptus tricornis, Carr. 



Coenograptus gracilis ?, Hall. Cliniacograptus caelatus, Lapw. 



Diplograptus foliaceus, Murch. 



A fine example of Dicranogr aptus formosus, Hopk., from 

 these beds at Castell is in the Jermyn-Street collection (Case 

 iv. yV). Hocks of corresponding age at Meadowtown near 

 Shelve have yielded me Diplograptus foliaceus, Murch., and 

 D. dentatus, Brongn. 



The Upper Llandeilo rocks of Abereiddy Bay have, up to 

 this time, proved barren of Graptolites. From the Upper 

 Llandeilo of Hagley, near Chirbury, I have collected Diplo- 

 graptus foliaceus, Murch., and Climacogr aptus Scharenbergi, 

 Lapw. From the Upper Llandeilo of Llandrindod Wells Mr. 

 Hopkinson sent me, some years ago, Climacogr aptus Scharen- 

 bergi, Lapw., C. ccelatus, Lapw., and Dicellograptus mof- 

 fatensis, Carr. From the same rocks near that town I have 

 this summer collected Diplograptus tricornis, Carr., D. folia- 

 ceus, Murch., Climacogr aptus ccelatus, Lapw., C. perexca- 

 vatus, Lapw., C. Scharenbergi, Lapw., and species of Dicel- 

 lograptus and Lasiograptus. 



At the village of St. Clear's, near Caermarthen, the bank of 

 the little river exposes a good section of highly fossiliferous 



* Hopkinson and Lapworlh, Quart. Journ. Geol. Soc. vol. xxxi. 

 p. 634; 



