554 R. H. Traquair — On a New Carboniferous Fish from Airdrie. 



III. — On Uronemus magnus, a New Fossil Fish from the Coal- 



Measures oe Airdrie, Lanarkshire. 



By E. H. TKiQUAm, M.D. 



THE specimen (No. 37,958 of the British Museum Collection), 

 which forms the subject of the present notice, is from the 

 Blackband Ironstone of Airdrie, and, I understand, from the same 

 bed which yielded the first known specimen of Anthracosaurus 

 BtisselU. The fossil is unfortunately very imperfect, though it dis- 

 plays a considerable portion of the body of a large fish lying on its 

 right side. Both the head and the caudal extremity, however, are 

 gone, nor is the ventral margin shown ; but the line of the back is 

 pretty nearly intact, and is seen to be bordered by the long dorsal fin 

 characteristic of Phaneropleuron and of JJronemus. What remains of 

 the body shows a confused mass of ribs, spinous processes, and inter- 

 spinous ossicles, compressed against a groundwork of what are 

 apparently large and very thin rounded scales. The specimen, 

 measuring 15^ inches in length, by 5^ inches in breadth at its broadest 

 part, presents thus a considerable part of the abdominal, with the 

 anterior part of the caudal region of a fish, which, when entire, must 

 have been in all probability more than two feet long. 



Scales. — From the manner in which these are squeezed together, it 

 is impossible to determine accurately their size and shape : to judge 

 from their lines of growth, however, they seem to have been 

 cycloidal, or perhaps acuminate-cycloid al, like those of Bhizodopsis, 

 and to have been of considerable size. On some parts of the fossil 

 impressions of portions of their attached surfaces may be seen, and 

 these show very fine close lines of growth, crossed by still more delicate 

 radiating strige, and places occasionally occur where the concentric 

 lines cease and only the radiating ones remain. What one is tempted 

 to consider the external surface of the scales shows a very beautiful 

 and exceedingly minute granulation, often passing into a fine granular 

 striation, by the granules becoming arranged in parallel rows. But 

 whether we are here dealing with the actual external ornament of 

 the scale, or with internal structure only, it is difficult to decide, from 

 the want of the counterpart of the specimen, and from the extreme 

 delicacy of the parts in question. 



Internal skeleton. — A mass of ribs, rather confused, is seen in the 

 anterior part of the specimen, and extends for about 6 inches back. 

 Each rib is stout, pretty strongly curved, enlarged at its head, nearlj'^ 

 cylindrical for a good part of its length, but getting laterally flattened 

 towards its termination, though in no case is the extreme point seen. 

 The most entire rib on the specimen measures 2|^ inches along its 

 curvature, and 2^^ inches directly from head to ventral extremity, 

 while its diameter at one-third of its length below the head is 

 y^ inch. A very delicate groove is seen in many instances, extending 

 down from the head for a little distance near the outer aspect of the 

 body of the rib. An internal tubular cavity, filled with white carbon- 

 ate of lime, is seen to traverse the greater part of the length of some 



