708 Davis — On the Fossil Fish- Remains of the Coal Pleasures of the British Islands. 



body may have been covered with shagreen, but in the siDecimens available for 

 observation the skin was without scales or other pi'otection. The spine was ap- 

 parently one-fourth to one-fifth of the entire length of the fish ; it was implanted 

 in the occipital cartilage without articulation. The vertebral column was noto- 

 chordal, more or less encircled by the bony extremities of the apophyses ; ribs, 

 short and rudimentary, were present, with the articulating extremity broad, and 

 the opposite one pointed. Immediately behind the spine there originated a dorsal 

 fin, which extended along the back to the caudal extremity. In addition to the fin 

 rays and the spinous jjrocesses attached to the vertebral column, there were two 

 series of interspinous bones. This arrangement extended to a short distance 

 beyond the ventral fin. The smaller interspinous bones, surapophyses of Fritsch, 

 next to the neurapophyses, then disappear, and the longer interspinous bones con- 

 tinue nearly to the caudal extremity of the body. A fin also extended along the 

 ventral surface of the body, and joining the dorsal one formed a single-lobed tail. 



Dr. Kner describes four or five gill arches, furnislied with a few long teeth. 

 The skull was of so soft and cartilaginous a nature that the orbits are obliterated, 

 and no evidence is afforded of any segmentation of the covering of the skull. The 

 constituents of the cranium and the jaws were recognized as consisting of cartilage 

 filled with closely approximating ossicular centres. This enamel-like arrangement 

 was compared by Bey rich to a species of mosaic. The upper jaws are stated to 

 consist of maxillary bones, with pre-maxillaries attached, both provided with 

 teeth. 



The organs attached to the ventral fins, considered by Dr. Geinitz to have 

 been suckers, were described by Dr. Kner as hooking organs similar to the claspers 

 of sharks found at the present time, and this opinion he enforced by the observa- 

 tion that some of the fishes possessed these appendages and others did not ; those 

 possessing them being the male fishes, and those devoid of them being females. 



Messrs. Hancock and Atthey found tlie teeth of Diplodus, associated with large 

 patches of thick granular substance resembling shagreen, in the Coal Measures of 

 Newsham and Cramlington, in Northumberland. This association led them to 

 write :* — " There can be little doubt that these shagreen-like patches are the 

 remains of the skin of some large fish, and that the Diplodi are dermal tubercles 

 in connexion with it, and analogous to the spinous tubercles of the Rays. At the 

 same time it must be admitted that it is possible enough that the larger specimens 

 may have clothed the lips or jaws with a spinous pavement resembling in arrange- 

 ment the oral armature of the Rays or Cestracions." The authors describe the 

 great variation in size and form of the so-called dermal tubercles, and recognize 

 that the D. minutus, Ag., belongs to the same species as D. gihhosus. It is also 



■•^' Nat. Hist. Trans. Northumberland and Durtam, vol. iii., p. 111. 1879. 



