534 J. E. Marr — The Wenlock and Jjudloio strata — 



jaws small, acuminate. Dorsal fins witliont spine. Trunk covered 

 witli minute stellate tubercles, gradually enlarging and passing on 

 the snout into the rostral teeth ; the lateral borders of the head, 

 the anterior border of the paired fins, and the sides of the tail 

 strengthened with dense patches of small, robust, smooth tubercles. 



Sclerorhynchus atavus. 

 1889. Sclerorhi/nchus atavus, A. S. Woodward, Cat. Foss. Fishes, B.M., pt. i. 

 p. 76, pi. iii. fig. 1, and Proc. Zool. Soc, p. 450, woodcut. 



1889. Sqiiatina crassidens, A. S. Woodward, Cat. Foss. Fishes, B.M., pt. i. p. 69, 



pi. ii. 



1890. Pristiophorus [Sclerorhynchus) atavtm, 0. Jaekel, Zeitschr. deutsch. geol. Ges., 



p. 117, pi. ii. fig. 1. 



1891. Pristiophorus atavus, 0. Jaekel, Archiv. f. Naturgesch., p. 43, pi. i. fig. 1. 



Type. Portion of rostrum ; British Museum. 



The type-species, attaining a length of about 0-85. Maximum 

 breadth across the pectoral fins nearly equal to the length of the 

 rostrum, which occupies about one-third of the total length of the fish. 

 Teeth vertically ribbed, at least on the inner face. Pelvic fins more 

 than half as long as the pectorals. Kostral teeth small and regularly 

 arranged, compressed to a sharp edge anteriorly and posteriorly. 



Formation and Locality. — Upper Cretaceous (Senonian) ; Sahel 

 Alma, Mount Lebanon, Syria. 



II. — On the Wenlook and Ludlow Strata of the Lake District. 



By J. E. Marr, M.A., F.R.S., Sec.G.S. 

 rpHE beds above the Borrowdale volcanic group, and below the 

 X Coniston Flags, have been treated in detail in other communi- 

 cations, but, notwithstanding all that has been written of the higher 

 Silnrian rocks of the Lake District, something remains to be said 

 about them. The classification adopted in this paper, reasons for 

 which will be subsequently given, is subjoined : — 



Kirkby Moor Flags = Upper Ludlow, 



Sti -fi h H* d " I ~ Passage between Upper and Lower Ludlow. 



Baunisdale Slates 



Coniston Grits ] = Lower Ludlow. 



Cold well Beds 



Brnthay Flags = Wenlock. 



These formations, it is well-known, are found principally in the 

 undulating country to the south of the Coniston Limestone outcrop 

 of the central region of the Lake District, and extend thence in au 

 easterly direction, forming the great bulk of the Howgill Fells, and 

 appearing finally in the neighbourhood of Settle. The Brathay 

 Flags are found in two exposures in the neighbourhood of Dufton, 

 on the west side of the Cross Fell inlier, indicating the probable 

 occurrence of a synclinal occupied by these Upper Silurian strata 

 under the newer rocks of the Eden Valley, and an outcrop of the 

 Coniston grits is found on the extreme north of the Cross Fell area, 

 pointing to the commencement of the Silurian rocks on the north 

 side of the great Lake District anticline. This isolated outcrop is 

 interesting, as the beds are here only thirty-five miles distant from 



