1898-1902 No. 33.] UPPER DEVONIAN FISH REMAINS. 51 



was a thickly armoured, powerful species, about 0.5 m. in length. 

 The posterior body was probably, - - as Pathen believed - - bare and 

 without scales, the anterior body on the other hand being protected by a 

 hard, almost rigid armour. The mouth was without jaw, and presumably 

 a suction month. A remarkable feature was the long arms, provided 

 with a kind of elbow, the distal portion of which in this family is almost 

 pointed like an awl. Many attempts have been made at solving the 

 problem of these extraordinary arm-like, jointed processes, that do not 

 appear to be homologous with the real pectoral fins of the fishes. ABEL 1 

 attempted recently to explain them as an apparatus for catching prey, 

 which operated in a manner similar to that of the claw of a lobster or 

 the arms of the Mantides. According to TRAQUAIR'S investigations it 

 appears to be doubtful whether the arms in question really possessed 

 such a large range of movement as the instruments of capture in the 

 case of living types. It seems to me to be more reasonable that the 

 creature employed them to fasten itself to its prey, which then could be 

 sucked at leisure-. The bare posterior body indicates that it was a 

 ground fish, -- as has been supposed in the case of Coccosteus, and 

 that it usually lay half buried in the mud. 



The two Psammosteus forms, ray-like, strongly armoured, jawless 

 tishes of considerable size, were presumably still more markedly ground 

 fishes. The armour was beautifully ornamented with fine denticles of 

 highly polished enamel, and the tail was armed above and below with 

 powerful fulcra, which must have served for defence. A large coccosteo- 

 morph fish, with the anterior body even more strongly armoured than 

 the preceding, was presumably less common than those already mentioned. 

 The thickness of one of these osseous plates is 0,7 cm. 



The hard and massive osseous plates in Ihe dermal skeleton of these 

 fishes, was undoubtedly a very effective protection against an enemy. 

 The most dangerous of the latter was the great Crossopterrygii, of 

 which several forms have been found, fishes of a more normal appearance 

 which were protected by means of thick scales of enamel. The largest 

 belonged to the Holoptychius Genus, was perhaps a metre in length, 

 with beautifully sculptured scales of a greater thickness than that of any 

 existing fish. The long tuft-shaped pectoral fins gave them a remarkable 

 appearance. In these formidable rapacious fishes the jaws were armed with 

 a double set of teeth. The outer row consisted of small flattened teeth, 

 the inner one of more extended, large and wedge-shaped teeth, with 



1 O. ABEL, Griindztige d. Palaeobiologie der Wirbeltiere, 1912, p 599. 



2 CF. KOKEN, Pisces, Zittel, Grundzuge der Pal. 2 Edition, II, 1911, p. 37. 



