270 DR R. KIDSTON AND PROFESSOR D. T. GWYNNE-VAUGHAN ON 
cortex of the stem separates it widely from Sutcleffia insignis, with which one might be 
tempted to compare it. “gg 
Locality.—Road Cutting at north end of Norham Bridge, Berwickshire. 
Horizon.—Calciferous Sandstone Series. 
D1IAGNosIs. 
Stenomyelon Tuedianum, Kidston, gen. et spec. nov. 
Stem monostelic, primary xylem without xylem parenchyma, divided more or less 
distinctly into three lobes by as many radiating and interrupted bands of parenchyma. 
Primary trachez porose on all walls. The protoxylems of the leaf-trace decurrent as 
exarch strands on the extremities of the lobes. Secondary thickening occurs. Secondary 
tracheze, with porose pits on radial walls only. Medullary rays numerous. Stele closely 
invested by a zone of sclerotic periderm. Leaf-traces depart successively from the 
extremities of the lobes and repeatedly divide in the cortex. Leaf-trace protoxylems 
become immersed. Outer cortex of the “ Sparganum” type. 
DESCRIPTION OF PLATES I.-IV. 
Puate I. 
Stenomyelon Tuedianum, Kidston. 
Fig. 1. General view of the specimen, showing a stem, s¢., and a portion of a leaf, 1. x24. (Slide 2093.) 
Fig. 2. Transverse section of the stem, showing the cortex flattened into a thin wing. x 24. 
(Slide 2089.) 
Fig. 3. Transverse section of the stem, showing a thicker and indented cortex. x2}. (Slide 2097.) 
Fig. 4. Transverse section of outer cortex of midrib of leaf, showing two long emergences; par., 
parenchymatous cortex. x13. (Slide 2094.) : 
Fig. 5. Transverse section of the small stem in Mr Matueson’s original block.. x9. (Slide 2107.) 
Fig. 6. Transverse section of stem, showing the beginning of the departure of a leaf-trace, 1.4.2, x 9. 
(Slide 2088.) 
Fig. 7. Do., Ut.1, the trace of the proceeding leaf already divided into two. x9. (Slide 2092.) 
Puate II. 
Fig. 8. Transverse section of stem, showing leaf-trace just free from primary xylem. x9. 
(Slide 2095.) 
Fig. 9. Do., leaf-trace passing through secondary xylem. x9. (Slide 2096.) 
Fig. 10. Transverse section of stem, showing leaf-trace free from secondary xylem; m.r., specially large 
medullary rays below the leaf-trace ; prx., single protoxylem at summit of lobe. x9. (Slide 2098.) 
Fig. 11. Transverse section of a lobe of the primary xylem with two decurrent leaf-trace protoxylems, 
pre. x35. (Slide 2091.) 
Fig. 12. Longitudinal section of central tracheze of primary xylem. x110. (Slide 2101.) 
Fig. 13. Longitudinal section of periphery of primary xylem, showing small scalariform elements, 
x 110. (Slide 2099.) 1 
