from the Carboniferous of Western Australia. 



entirely unlike the rotary hinge-movement characteristic of the 

 pectoral spines of Siluroid fishes." 



" The spine is composed of parallel rods in close apposition. The 

 anterior edge being oblique, the extremities of the rods terminate 

 successively at the border, which is trenchant, constituting the 

 offensive part of the spine. The edge is hardened, and the adjacent 

 parts of the spine thickened, and in some cases roughened by a 

 deposit of a hard substance resembling enamel. It is either straight 

 or regularly undulate or serrate, with recurved, acute, tooth-like 

 processes. The smaller species exhibit the serrate character, the 

 larger the regular border. In either case a most formidable weapon 

 is indicated, not less admirable than those already described from 

 Palasozoic rocks. There is a considerable resemblance between the 

 serrate type and the spines of the Carboniferous genus Edestus, in 

 which the teeth are more developed and denticulate." (E. D. dope. 

 Report of the United States Geological Survey of the Territories. 

 F. V. Hay den, U.S. Geologist-in-charge, vol. ii. p. 244b. 4to. 

 Washington, 1875.) (See Woodcut, infra, Fig. 4. 



Fiar. 2. 



Fur. 3. 



Fiff. 4 



Fie. 5. 



Fig. 2. Pectoral Spine of Aspredo Icevis ; (recent) Surinam. 

 „ 3. „ ,, Doras, sp. ,, S. America. 



„ 4. „ ,, Pekcopterus, sp.. Chalk, Sussex. 



„ o. Dorsal Spine of Hybodus, "Wealden, Sussex. 



