F. J. North — The genus Syringothyris. 393 



Bibliography. 



Bain, A. G., "On the Geology of South Africa" : Trans. Geol. Soc. Lend,, 



ser. II, vol. vii, pp. 175-92, 1856. 

 FkaaS, E., Science, new ser., vol. xiv, pp. 210-12, 1901. 

 Hatcher, J. B., " Origin of the Oligocene and Miocene Deposits of the Great 



Plains" : Proc. Amer. Phil. Soc, vol. xli, pp. 113-31, 1902. 

 Leidy, J., The Extinct Mammalian Fauna of Dakota and Nebraska. 



Philadelphia, 1869. 

 Matthew, W. D., "Fossil Mammals of the Territory of North-Eastem 



Colorado " : Mem. Amer. Mus. Nat. Hist., vol. i, pt. vii, 1901, 



III. — On the genus Stein gotbysis, "Winchell. 



By Frederick J. North, B.Sc, Assistant in the Geological Department, 

 King's College, London. 



(PLATE Xn.) 



1. Introduction. 



2. Historical Eeview. 



3. General Account of the Plate-like Structures in the Pedicle Valve of 



Syringothyris. 



4. Detailed Account of the Structure of the Tube-bearing Plate (Transverse 



Plate) in a specimen of Syrhigothyris aff. carteri (Hall). 



5. Eelation between Syringothyris and certain Spirifers ; and the Origin 



of Syringothyris in North America. 



1 . Introduction. 



rpHE following account of the genus Syringothyris is the result of 

 JL work undertaken at the suggestion of Professor T. F. Sibly, and 

 is intended as a preliminary to a revision of the British species of 

 that genus, which I hope to present at some future date. 



Although it has long been known that Syringothyris possessed 

 a distinctive internal structure referred to as a syrinx, or "a split 

 tube between the dental plates ", the exact relations of that structure 

 had not been worked out, and it therefore seemed advisable to obtain 

 a clear understanding of the characters of the genus, before attempting 

 to deal with the mutual relations of its species. 



To Professor Sibly I have to express my thanks, not only for his 

 valuable advice and assistance while the work has been in progress, 

 but also for his kindness in placing the necessary material at my 

 disposal for study. My thanks are also due to Dr. A. Smith Woodward, 

 P.E,.S., for permission to examine and section specimens in the 

 British Museum (Natural History), South Kensington, and to 

 Mr. R. B. Newton, F.G.S., for assistance in searching the collections 

 in the Museum. 



2. Historical Review. 



The shell now known as Syringothyris cuspidata (Martin) was 

 first described in 1796 by William Martin,^ who named it Anemia 

 cuspidata. The true nature of the fossil Brachiopoda had not at that 

 time been recognized, and Martin regarded his shell as an Anomia, 

 comparing its triangular fissure with the hole in the attached valve 

 of that lamellibranch. The type-specimen, which is now preserved 

 in the Sowerby Collection in the British Museum (Natural History), 



' Martin, 1796, pp. 44-50. 



