VI 



In his later study of the Echinoidea, he commenced with those in 

 beds the Corals of which he had already examined, among the most 

 remarkable being those from South Australia, which he described in 

 a series of papers dating from 1864 to 1887. It was apparently his 

 interest in the origin of this fauna, with its mixture of Cretaceous 

 and Cainozoic genera, that led him to take up the Indian Echinoids, 

 which, in conjunction with Mr. W. Percy Sladen, F.L.S., he mono- 

 graphed with such detail and care. 



He studied with especial interest the Echinoids of the Cenomanian, 

 and by the aid of the small collections of the Rev. W. F. Holland, in 

 Sinai, and of Dr. Carter, in South Arabia, he gradually built up the 

 connexion between the European fauna and that of Northern India. 

 By his comparison of those of the Peninsular and Extra-Peninsular 

 areas he demonstrated the existence of the land-barrier that stretched 

 across India, and away to the south west, of which such important 

 use has been made in recent controversy. His views on geographical 

 distribution were original, and had been carefully matured ; his 

 lecture on " The Formation of the Main Land Masses " showed that 

 he did not accept the views of the permanence of oceans and con- 

 tinents, a subject upon which he was competent to speak with 

 authority. His paper on " The Fauna of the Alpine Lakes " prob- 

 ably dealt the most serious blow ever struck to the theory of the 

 glacial origin of the Swiss lake-basins. 



But though Professor Duncan did not regard morphology as the 

 highest end, he did not by any means neglect it ; thus our knowledge 

 of the perignathic girdle of the Echinoids and its value in classifica- 

 tion we owe mainly to him ; while his remarkably suggestive and 

 original essay on the structure of the ambulacra of the regular 

 Echinoidea, perhaps his most masterly piece of work, has gained the 

 highest praise even from men opposed to his views. 



In addition to his contributions to paleontology, he has done much 

 in zoology; he wrote a series of papers on the anatomy of the 

 Temnopleuridee, Saleniida3, and other groups of the Echinoidea, and 

 described, amongst others, the Madreporaria of the " Porcupine " 

 Expedition, the Ophiurids and Corals of Mergui, and, in conjunction 

 with his constant collaborator, Mr. Sladen, the Echinodermata from 

 Greenland. Two of his most valuable works are " The Revision of 

 the Madreporaria," and his " Revision of the Genera and Great 

 Groups of the Echinoidea." The former was issued in 1885, and con- 

 sisted of diagnoses of every genus of Coral (excluding the Rugosa), 

 and of a classification which has not yet been supplanted. His 

 revision of the Echinoidea made a great advance in our knowledge 

 of every order. The application of his own discoveries on the ambu- 

 lacral structure enabled him to bring the Palechinoidea from chaos 

 into order, and to replace the artificial arrangement of the Diadema- 



