President's Address. 153 



was completely out of his reckoning. The diphy cereal tail is 

 in reality a more primitive or emhryonic form than even the 

 heterocercal, of which the modern homocercal tail is again a 

 further specialisation. That this is the case is evident enough 

 to any one who will carefully compare a proper series of tails 

 of recent and fossil fishes, but Professor Alexander Agassiz 

 has recently put the matter in a perfectly clear and unmis- 

 takable light by showing that the tail in embryo Pleiironec- 

 tidce is first diphycercal (leptocardial), then heterocercal, and 

 finally assumes the homocercal form of the adult in which 

 the heterocercy becomes to external appearance completely 

 obliterated. 



At this stage of our sketch of the history of Scottish Fossil 

 Ichthyology, it will be appropriate to refer to what has been 

 done by Sir Philip Grey-Egerton, glad as we all are that the 

 veteran naturalist is still living amongst us, and continuing 

 to take the warmest interest in the progress of the science 

 to which he has himself contributed so much. 



Sir Philip has not in his writings sought to alter the clas- 

 sification of Agassiz save in one or two points of secondary 

 importance, but he has busied himself with the description 

 of new genera and species, so largely supplied by his own 

 magnificent collection as well as by that of his close personal 

 friend, the Earl of Enniskillen, to whom also the friends of 

 fossil ichthyology owe a lasting debt of gratitude. Although 

 Sir Philip's descriptions mainly relate to fishes from the 

 newer formations in England, he has also made some im- 

 portant contributions to our knowledge of Scottish forms. 

 In his paper on Pterichthys (1848), written in conjunction 

 with Hugh Miller, he corrected some of the mistakes into 

 which Agassiz had fallen with regard to the arrangement of 

 the plates in that genus. In another communication, " On 

 the Nomenclature of the Devonian Fishes," he offered some 

 able criticisms on Professor M'Coy's work in that department, 

 and added as a supplement a series of interesting extracts 

 from letters by Hugh Miller on the structure of Coccosteus. 

 The tenth decade of the Geological Survey, published in 1861, 

 contains also from Sir Philip's pen a description of Tristi- 

 chojpterus alatus, one of Mr Peach's most interesting dis- 



VOL. V. L 



