226 BR. V. J. NORTH OX [vol. lxxvi, 



Plate XII. 



Fig - . 1. Syrvtigothyris cuspidata,mat. cuspidata. (a) Brachial valve : (b) pro- 

 file. (The same as PI. XI, fig - . 8.) D„ subzone ; Castleton (Derby- 

 shire). (Coll. by the late Dr. Wheelton Hind.) 



2. Syi ingothyris cuspidata, mut. cuspidata, distorted specimen, (a) 



Profile ; (b) brachial valve. D zone ; Little Island (Cork). (Sedg- 

 wick Museum Coll., on Tablet 945.) 



3. SyringotTvyris elongata, sp. nov. The area of the pedicle- valve, slightly 



crushed. Z zone ; Malahide (Comity Dublin). (Geological Survey 

 of Ireland Coll. Figured by permission of the Director.) 



4. Syringothyris elongata, sp. nov. (o) The area of the pedicle-valve ; 



(b) profile ; (c) the brachial valve. C zone ; Adare (Limerick). 

 (Geological Survey of Ireland Coll. No. 1492. Figured by permission 

 of the Director.) 



5. Syri/ngothyris elongata. sp. nov. (a) The area of the pedicle- valve : 



(b) brachial valve. D zone ; Kniveton (Derbyshire). (Coll. by the 

 late Dr. Wheelton Hind.) 



Plate XIII. 



(Note. — Figs. 1-5 are from exfoliated specimens, and show no trace of the 

 imbricate structure (fig. 16) seen in well-preserved examples of Tylo- 

 thyris -. such specimens are rare.) 



Fig. 1. Tylothyris laminosa, mut. y. Imperfect pedicle-valve. Z., subzone ; 

 Twyn-yr-odin (Glamorgan). (Coll. of Principal T. F. Sibly, 

 20474 G 5.) 



2. Tylothyris laminosa, mut. y. Brachial valve. Horizon y ; Alps Quarry, 



Wenvoe (Glamorgan). (Coll. by the writer, now in the National 

 Museum of Wales. Beg. No. 19246 G 3.) 



3. Tylothyris subconica castletonensis, subsp. nov. Brachial valve. D 2 



subzone ; Castleton (Derbyshire). (Coll. by the late Dr. Wheelton 

 Hind.) 



4. Tylothyris subconica, castletonensis. (a) The area ; (b) profile. D._, sub- 



zone ; Castleton (Derbyshire). (Coll. by the late Dr. Wheelton 

 Hind.) 



5. Tylothyris subconica- subconica (Martin), (a) Brachial valve ; (b)area; 



(c) profile. D., subzone ; Settle (Yorkshire). (Sedgwick Museum 

 Coll., Tablet 501.) [Fig. 5 c slightly exaggerates the curvature of 

 the area : it is usually almost flat.] 



6. Punctospirifer scabricosta, sp. nov., mut. redesdalensis. Brachial valve. 



D t subzone ; Bedesdale (Northumberland). (Coll. of Prof. E. J. 

 Garwood.) 



7. Spiriferina, perplicata, sp. nov. (a) Brachial valve ; (b) profile ; 



(c) pedicle-valve. D„ subzone ; Treak Cliff, Castleton. (Coll. of 

 Mr. J. W. Jackson, F.G.S., Manchester.) 



8. Spiriferina, octoplicata, mut. D (J. de C. Sowerby). Brachial valve. 



Parkhill (Derbyshire). (National Museum of Wales, 19246 G 10.) 



9. Spiriferina octoplicata, mut. S. Portion of brachial valve. Horizon y ; 



Little Island, Barry (Glamorgan). (Coll. of Principal T. F. Sibly. 

 20474 G 6.) 



10. Spiriferi/na perplicata, mut. K. Brachial valve. K., subzone ; Walton 



Castle, Clevedon (Somerset). (Coll. of Mr. J. W. Tutcher.) 



11. Spiriferina insciilpta (Phillips). D, subzone ; Treak Cliff, Castleton. 



(Coll. of Mr. J. W. Jackson, F.G.S.) 



12. Tylothyris laminosa, mut. y. Cast of the interior of the pedicle- valve. 



Cj subzone (laminosa dolomite) ; Collafield, north of Littledean 

 (Gloucestershire). (Coll. of Principal T. F. Sibly, 20474 G 7.) 



| November 30th, 1920.] 



