INTRODUCTION. Vi 
constant need for caution and reflection. Before the beginner yields 
to the temptation of describing ‘ new species,” which is easy enough, 
let him first gain the knowledge and experience which will teach 
him how one form links on to another, and thus avoid the undue 
multiplication of synonyms. 
Till quite recently our collection of Echinoderms was particularly 
poor in British specimens ; that we have now a splendid series illus- 
trative of the fauna of the West coast of Scotland is due to Dr. John 
Murray, as the repeated citation of his name will abundantly show, 
and he deserves our sincerest thanks ; the Hon. Alfred E. Gathorne- 
Hardy has from time to time presented us with valuable and well- 
preserved specimens from Loch Craignish; while from the East 
of Scotland I have been much aided in forming a collection by 
Dr. Sutherland of Invergordon, Mr. W. Duncan of Montrose, and 
Mr. George Sim of Aberdeen. For specimens from the East coast 
of Ireland we have been aided by the gifts of the Belfast Natural 
History Society; I owe to the friendly kindness ‘and scientific 
enthusiasm of Professor A. C. Haddon numerous opportunities of 
inspecting, and ofttimes keeping for our Collection, the results of 
dredgings in the Irish Seas, made under the auspices of the Royal 
Irish Academy or the Royal Dublin Society. The deep-sea expe- 
dition of 1889, which Dr. Giinther induced the Rev. W. S. 
Green to undertake in the ‘ Flying Fox,’ resulted in a very valuable 
and instructive series of Echinoderms. My thanks are also due to 
Lord Walsingham, F.R.S., Prof. Herdman, F.R.S., Prof. McIntosh, 
F.R.S., Mr. Howse of Newcastle, to Mr. G. C. Bourne, formerly of 
the Marine Biological Laboratory at Plymouth, and Dr. Grenfell, for 
assistance offered and given. Mr. R. L. Spencer has repeatedly 
sent me objects of interest from the Channel Islands. I have kept 
to the last, because I desire it to be mentioned by itself, the name of 
the Rev. Canon Norman, F.R.S., whose interest in the marine 
British fauna is such that, in the midst of arduous and responsible 
duties, he has always found time to answer the numerous questions 
I have asked him, or to lend or give me specimens which would help 
me in my work. 
As many of our species are more familiar to Scandinavian natu- 
ralists than ourselves, 1 have had to ask for, and have received, 
