part 2] SYRINGOTHYRIS AND SPIRIFERINA. 225 



29. C. Schucheet. — ' On Syringothyris Winchell, & its American Species' 



9th Ann. Rep. N.Y. State Geologist (1890) pp. 28-37. 



30. T. F. Sibly. — 'On the Carboniferous Limestone (Avonian) of the Mendip 



Area (Somerset), with especial reference to the Pala;ontological Sequence ' 

 Q. J. Gr. S. vol. lxii (1906) pp. 324-80. 



31. T. F. Siblt. — ' The t'aunal Succession in the Carboniferous Limestone (Upper 



Avonian) of the Midland Area' Q. J.G.S. vol. lxiv (19u8) pp. 34-82. 



32. J. & J. de C. Sowekby. — 'The Mineral Conchology of Great Britain ' 



1812-1845. 



33. A. Vacghan— 'The Palseontologieal Sequence in the Carboniferous Lime- 



stone of the Bristol Area' Q. J.G.S. vol. Ixi (1905) pp. 181-307. 



34. A. Vaughan. — ' An Account of the Faunal Succession & Correlation of the 



Carboniferous Rock* at Rush (County Dublin) ' Q.J. G. S. vol. lxii (1906) 

 pp. 295-323. 



35. A. Vaughan. — 'Correlation of Dinantian & Avonian ' Q. J.G.S. vol. lxxi 



(1915) pp. 1-52. 



36. S. Welleb. — 'The Mississippian Brachiopoda of the Mississippi Valley Basin ' 



Illinois Giol. Surv., Monogr. I (1914) ; {Syringothyris & Pseudosyrinx). 



37. H. S. Williams. — ' Recurrent Trovidoleptus Zones in the Upper Devonian 



of New York ' U.S. Geol. Surv. Prof. Paper 79 (1913) pp. 61-62. 



38. A. Winchell. — ' Description of the Fossils of the Yellow Sandstones lying 



beneath the Burlington Limestone, at Burlington, Iowa' Proc. Acad. Nat. 

 Sci. Philad. ser. 2, vol. vii (1863) pp. 2-25. 



EXPLANATION OF PLATES XI-XIII. 1 



[All figures are of the natural size, unless otherwise indicated.] 

 Plate XL 



Fig. 1. Syringothyris principalis, sp. nov. Pedicle-valve. K zone ; Trot's 

 Corner, Mendip area. (Coll. of Principal T. F. Sibly, 20474 G l.) 2 



2. Syringothyris 'principalis, sp. nov. Pedicle-valve. K 2 subzone ; Howie 



Hill, Mitcheldean district. (Coll. of Principal T. F. Sibly, 20474 G2.) 



3. Syringothyris cuspidata, mut. cyrtorhyncha. (a) Brachial valve ; 



(6) profile. Z t subzone; Avon Section (south side), Bristol. (Coll. 

 by the writer, now in the National Museum of Wales. Reg. No. 

 19246 G 2.) 



4. Syringothyris cuspidata, mut. exoleta. (a) Brachial valve ; (b) profile. 



C 2 subzone ; Black Rocks, near Sutton (Glamorgan). (Coll. of Prin- 

 cipal T. F. Sibly, 20474 G 3.) 



5. Syringothyris cusx>idata, mut. exoleta. Waulsortian ' knoll '-type. 



(«) Brachial valve ; (b) profile. C zone ; Momane (Limerick). 

 (Coll. of the Geological Survey of Ireland. No. 1142. Figured by 

 permission of the Director.) 



6. Syringothyris cuspidata, mut. cyrtorhyncha. Internal cast of the 



pedicle-valve, showing the infilling of the syrinx and its slit. 

 Z zone; Mitcheldean Quarry (Gloucestershire). (Coll. of Principal 

 T. F. Sibly, 20474 G 4.) 



7. Syringothyris cuspidata, mut. cuspidata. Specimen with asymmetric 



area (pedicle-valve, looking towards the apex). Upper Avonian ; 

 Ell Bolton, Cracoe (Yorkshire). (Coll. by the late Dr. Wheelton 

 Hind.) 



8. Syringothyris cuspidata, mut. cuspidata. Pedicle-valve, looking to- 



wards the apex. D 2 subzone ; Castleton (Derbyshire). (Coll. by 

 the late Dr. Wheelton Hind.) 



1 The cost of the drawings from which these Plates and other illustrations 

 are reproduced has been defrayed by a grant from the Dixon Fund of the 

 University of London. 



2 Principal Sibly has now presented to the National Museum of Wales, 

 Cardiff, all his specimens that have been figured or mentioned in this paper, 

 and their registration-numbers are given above. 



