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ON A MEGALICHTHYS PROM THE YORKSHIRE 

 COALFIELD. 



By L. C. MIALL, F.L.S., F.G.S., 



Professor of Biology at the Yorkshire College, Leeds. 



The genus Megalichthys, of which fragmentary remains are common 

 in coal shale, was first named by Agassiz from a fine skull which he 

 found in the Leeds Museum, and from less perfect specimens 

 collected by Dr. Hibbert at Burdiehouse. Subsequent discoveries 

 brought to light various details of structure, and the zoological 

 position of this Ganoid fish has gradually been elucidated with 

 sufficient exactness. Among the most instructive specimens are those 

 procured by Mr. John Ward of Longton, which form part of his 

 magnificent collection. The completest and best preserved of all 

 the known examples of MegaHchthys is, however, the fine fossil added 

 last year to the Leeds Museum. It was discovered at Mr. F. B. 

 Ellison's colliery, near Idle, in the roof of the Halifax Hard Bed, 

 and was extracted in a singularly perfect state by the pit manager, 

 Mr. Andrew Oldroyd. By Mr. Ellison's generous gift the fossil 

 became the property of the Leeds Philosophical Society. It measures 



3 feet 8 inches in length, of which the head includes about lo inches, 

 and the tail (which is imperfect) about a foot. The full length of 

 such a fish as yielded the large skull figured by Agassiz would be 



4 or 5 feet. 



Plate I shows the general proportions of the fish. At the head 

 end is seen the lower jaw, and enclosed by it the jugular plates which 

 defended the floor of the mouth. Further back, the small scales 

 which invest the pectoral fins are visible. Regularly disposed 

 lozenges of glittering enamel cover the rest of the under surface. At 

 the root of the tail are three large scales, which may be termed the 

 pelvic scales, and outside these are the remains of the ventral fins. 

 The anal fin is quite distinct, and unusually far back. The structure 

 of the paired fins, to which much importance is attached by 

 systematists, has not been hitherto clearly made out. It appears that 

 a pair of large basal scales or fulcra support the base of each fin, that 

 a row of smaller scales lies along the inner border, and a shorter row 

 along the outer border; lastly, that the space between these two rows 

 is occupied by a crowd of very small scales. The large scales no 

 doubt invested the more rigid, and the small scales the more flexible 

 parts of the fin, and we thus gain some insight into the structure of 

 the underlying skeleton, of which no trace is preserved. The fins of 



Jan. 1885. G 



