vm 



PBEFACE. 



To Mr. Hyiidman, of Belfast, Mr. Tliompson's associate in 

 dredging excursions and his cliosen companion in working out the 

 MoUusca, Articnlata, and Eadiata, the manuscript was also sub- 

 mitted, and received many emendations and improvements which 

 he alone could have supplied. 



From the scrupulous care with which every portion of the 

 manuscript was thus edited and revised, I can say without hesita- 

 tion that all was done that lay in our power, to bring forward 

 fully and fairly the materials which Mr. Thompson had for years 

 been accumulating. And yet with all of us there was a deep 

 conviction that the result so attained must needs be imperfect. 

 "We could deal only with the materials which we found ; we could 

 give only what Thompson had bequeathed. Had his life been 

 spared he would doubtless have brought collateral knowledge to 

 illustrate what to us was only a simple statement. He would 

 have expanded what to us were merely the hurried memoranda of 

 the moment, relative to some ascertained fact. He might in some 

 instances have condensed and brought under comprehensive 

 generalization more than one series of recorded phenomena. We 

 feel, therefore, that we have claims on the consideration and m- 

 dul'^'ence of those readers Avho are pursuing in a truthful and 

 earSest spirit the study of any department of natural science. 



The kindness and forbearance usually accorded to a posthumous 

 work will not be lessened by the fact, that one of those to whom 

 the publication had been intrusted did not live to complete his 

 allotted task. Mr. Jas. E. Garrett, my beloved and lamented co- 

 trustee, died of fever in Httle more than three years alter his Iriend 

 Mr. Thompson. The painful duty then devolved on me of receiv- 

 ing both his manuscripts and the originals, together with those 

 memoranda which he had written for his guidance m the work he 

 had so nearly completed. To Dr. Dickie I turned in this new 

 emergency, and the little that remained to be done was accom- 

 pHshed by him, with such co-operation as it was in my power to 



afford. 



Enough has been said to indicate the nature and extent ol the 



as "mv friend Ball," "Mr. Ball," " R. Ball, Esq.," and "Dr. Ball," it was 

 thourhl better to ad'opt the latter designation throughout, f ho"g\--- ^^^^^^ 

 notes%vere written many years before that well-merited honour had been con- 

 ferred. The same plan was adopted with regard to the names of two other 

 friends, Professor E Forbes and Professor AUman. Notes contr.bu ed by Dr 

 Ball, while these sheets were passing through the press, are mdicated by the 

 signature " R. Ball."— Ed. 



