126 NATURAL SCIENCE. August. 



Geological Society in 1858 he gave a detailed description of the 

 structure of the shields of Ceplialaspis and Ptevaspis, finally demon- 

 strating that these remarkable Devonian fossils must be vertebrates 

 of some kind. He even speculated (as it now appears) somewhat 

 wildly, remarking on the certainty that these ancient creatures must 

 be either ganoids or teleosteans ; hence, said he, the earliest fishes 

 were not the lowest in the scale, as was commonly assumed. His 

 most original memoir of all appeared three years later as a " Pre- 

 liminary Essay upon the Systematic Arrangement of the Fishes of the 

 Devonian Epoch," forming the greater part of Decade X in the 

 Memoirs of the Geological Survey. Here, for the first time, the 

 fringe- finned fishes (Crossopterygii, as they were then termed) were 

 clearly separated from the higher ganoids, and an entirely new idea 

 was thus introduced into the method of classification. The recog- 

 nition of the Crossopteryii was the first step to our modern conception 

 of the evolution of the fish-class. We now recognise that all the 

 earliest types of fishes had lobate fins, while these have gradually 

 become shortened up and replaced by long dermal fin-rays in the more 

 modern types. 



The Crossopterygian fishes were investigated by Huxley in great 

 detail, and his memoir of 1861 was followed in 1866 by another 

 Decade of the Geological Survey dealing exclusively with the family 

 of Coelacanthidae. Here this group was first scientifically defined, 

 and it was particularly described as an example of a persistent type. 

 The various genera of the family, from Ccelacanthus of the Lower 

 Carboniferous to Macvopoma of the Upper Chalk, differ from each 

 other only in the slightest particulars ; while the individuals repre- 

 senting them are comparatively abundant throughout the whole series 

 of strata in which they occur. 



Huxley's tentative conclusions as to the other Devonian fishes, 

 however, have not stood the test of subsequent research so satis- 

 factorily as his results from the Crossopterygians. Whatever the 

 anomalous fish Coccosteus may be, present knowledge seems to demon- 

 strate that it has not the remotest connection with the Siluroids, with 

 which Huxley- compared it. There can also be little doubt that 

 Ceplialaspis and Ptevaspis are limbless creatures below the fishes ; 

 while the Acanthodians are almost certainly specialised Elasmo- 

 branchs. 



The work on the fringe-finned fishes seems to have been first 

 stimulated by the Rev. John Anderson, D.D., who submitted to 

 Huxley some beautiful specimens from the Upper Old Red Sand- 

 stone of Fifeshire to be described in his well-known volume on 

 " Dura Den," published in 1859. The required contribution was 

 duly made, and then followed the memoirs to which we have just 

 referred. These may truly rank as monographs, involving much 

 laborious research. In the same category may also be placed the 

 memoirs on the gigantic Siluro-Devonian Crustacea (in collaboration 



