PLATE VI. 



FIGS. PAGE. 



Olenus cataractes, Salter. 56 



1. Specimen showing the points of the thoracic pleurae. The last thoracic segment appears 

 to be fused with the tail, which accordingly bears two spines on the left-hand margin, 

 instead of one. Lower Lingula Flags, Trefgarn Bridge, Haverfordwest. Collected by 

 Mr. V. M. Turnbull. Sedgwick Museum. Nat. size. 



Olenus mundus, sp. nov. 58 



2, :!. Forms supposed to be adult. Lower Lingula Flags, Trefgarn Bridge, Haverfordwest. 

 Collected by Mr. V. M. Turnbull. Sedgwick Museum, x 4. 



4, 5. Young forms. Lower Lingula Flags, Trefgarn Bridge, Haverfordwest. Collected by 

 Mr. V. M. Turnbull. Sedgwick Museum, x 20. 



Olenus longispinus (Belt). GO 



6. Probably one of Belt's types. Locality uncertain (labelled Conocoryplie huccphala, Upper 



Ffestiniog Beds, Dolgelly; but the name and probably the horizon are incorrect). 

 British Museum, I 7592. (Belt Collection.) x If 



7. A shellac cast of a specimen now unknown. Upper Dolgelly Beds, Dolgelly. British 



Museum, I 7577. (Belt Collection.) x 1£. 



Parabolina spinulosa (Wahlenberg). 62 



8. A rather small specimen. Upper Lingula Flags, Rhiwfelyn. Mr. G. J. Williams' 

 Collection. (Drawn from an artificial cast of the specimen, which is an external 

 mould.) x 11. 



!). Specimen of about the average size. The two points behind the axis of the tail are present 

 but indistinct. Lingula Flags, Rhiwfelyn. Mr. G. J. Williams' Collection. x H. 



10. Broad form. Upper Lingula Flags, Naut Cistfaen, Llyn Tryweryn. Mr. G. J. Williams' 



Collection, x If. 



11. Small form with very short pleural spines, probably young. Upper Lingula Flags, 



I.I \ n Tryweryn. Mr. G. J. Williams' Collection, x '6. 



Parabolinella williamsoni (Belt). G4 



12. Cranidium, parts of thorax, and tail, probably in their natural rel itive positions. Upper 

 Lingula Flags, Moel Gron. Sedgwick Museum. (Drawn from an artificial cast of the 

 specimen, which is a mould. The counterpart of the specimen is in the British Museum, 

 59291. Figured by Mr. F. R. C. Reed as Olenus [Parabolinella] plant), Geol. Mag., 

 1900, pi. xii, fig. 1.) Nat. size. 



