ON MEGALICHTHYS 317 



fish, and its greatest length is about forty centimetres, while 

 it measures about twenty centimetres at the widest part. In 

 some places the original material has been replaced by 

 pyrites, and the part of the fish which has been collected and 

 forms the specimen is broken in several directions. 



The anterior portion of the fossil clearly shews a consider- 

 able part of the pectoral fins, which seem to be nearly in their 

 natural positions. Further back the arrangement of the 

 body scales is well shewn. Both pectoral fins illustrate very 

 well the obtuse lobate character of the anterior paired 

 appendages of Megalichthys. In the case of the left pectoral 

 the scales of the lobe are well preserved, and their arrange- 

 ment and relation to the fin rays can be clearly made out. 

 There are traces of the underlying bones in the region anterior 

 to this fin, but they are hardly sufficiently clear to admit of 

 description. There is an acutely lobate scale imperfectly shewn 

 in a central anterior position ; this is perhaps a displaced 

 basal scale or fulcrum, belonging to the left pectoral fin. The 

 dichotomy of the fin-rays is to be clearly seen in both the fin- 

 fringes preserved in the specimen, but particularly in that of 

 the right pectoral ; here too the punctate surface of the ganoin 

 is particularly well illustrated by some of the proximal 

 elements. In places where the fin-rays are broken away the 

 underlying body scales are exposed to view. A considerable 

 expanse of the fringe of each fin forms a very interesting 

 feature of the specimen, but even more interesting is a large 

 scale lying on the pre-axial side of the lobe of the right 

 pectoral fin. Its basal (anterior) portion is missing, as the 

 edge of the specimen cuts the scale, but that part of it now 

 seen is 3*3 cms. in length and 2'2 cms. in width at the widest 

 exposed part. The bright surface is the same as that which 

 characterises all the neighbouring scales, and the punctate 

 appearance of the scale is similar to, though not so marked 

 as, that of some of the scales of the fin-lobe. This scale 

 differs, however, from the other scales in both size and shape ; 

 its dimensions have already been given. In shape it is 

 acutely lobate like the large imperfectly shewn scale already 



