ON MEGALICHTHYS 319 



in the median line in the caudal region or in other places where 

 the natural curvature of the body was markedly acute, and 

 very convex scales were of use as a protection. 



The use of these scales is admirably seen in the whole fish, 

 preserved in the Leeds Museum, in which such scales occur 

 in relation to the left pectoral fin, and in the ventral caudal 

 region. That the convexity is natural is seen where the 

 scales have been subjected to pressure ; in such cases a median 

 fracture is a common feature. Among the Manchester 

 Museum specimens, in addition to L.8328 and W.817, which 

 both shew convex scales, L. 10114 ("Cannel, Middle Coal 

 Measures, Wigan (?), Scales of Megalichthys hibberti ") is 

 also of interest since one of the scales exhibits the median 

 fracture. 



Part II. 



A New Description of the Species Megalichthys 

 hibberti. 



A consideration of the material described in the earlier part 

 of this paper, and a correlation of data given there with the 

 results arrived at by others, make it possible to suggest a more 

 complete description of Megalichthys hibberti than has pre- 

 viously been presented, and to prepare restorations of the fish 

 to accompany the description (text-figures 2 and 3). 



Megalichthys hibberti. 



The body is fusiform, robust, elongated, and somewhat 

 depressed, especially near the anterior end. The head and 

 opercular fold occupy about one-fifth the total length of the 

 fish. 



The scales are rhomboidal, slightly overlapping, and covered 

 externally with a layer of finely punctate ganoin. The exposed 

 surface, while rhomboidal in outline, has more or less 

 rounded angles ; the under surface is bony and serves for 

 attachment. The upper edge of the base carries an oblique 



E 



