INTRODUCTION. 
Onz of the objects of the present Catalogue is to supply the students 
of the British marine fauna with a handbook by means of which, it 
is hoped, they may be able to recognize such members of the very 
well-defined group of Echinoderma as they may collect in their 
expeditions to the sea-shore or in more extended dredging excur- 
sions. ‘The study of Starfishes and Sea-Urchins, which may be 
taken as the English for Echinoderma, has long been a favourite 
pursuit with British naturalists, owing largely to the peculiar 
charm of one of the most popular of Mr. Van Voorst’s well-known 
series, Professor Edward Forbes’s ‘ British Starfishes.’ So far as 
that volume is the work of an enthusiastic and experienced field- 
naturalist, it does and will always hold the chief place in the regard 
of every lover of Natural History, and what follows here must not 
be thought of as attempting to oust Forbes’s book from its position. 
Unfortunately, however, the progress of zoological science is still 
marked by considerable changes in nomenclature, and from this 
point of view Forbes’s work has long been out of date. On the 
other hand progress is, fortunately, marked by the discovery of new 
or exotic species in our seas, and by the union of forms which have 
been incorrectly regarded as specifically distinct. While Forbes 
enumerated (omitting the Gephyrea, which are not now regarded as 
Echinoderms) tifty-five species, there are contained in the present 
Catalogue one hundred and thirty-two; but of the fifty-five, eight 
are here regarded as synonyms, one (Arachnoides placenta) is expelled 
from the list, and Psolinus brevis remains as great a mystery to me 
as to many others. ‘The great increase in the number of species is 
due, ghietly, to the dredgings at depths which Forbes believed to be 
azoic, The inclusion of species known fromthe Faeroe Channel, which 
