INTRODUCTION. 
The following List is intended to serve various purposes : First, it 
attempts to provide a complete index to every name that has ever been 
applied to a real or supposed Blastoid genus or species. Secondly, it 
indicates which of those names are now considered valid, and which 
are believed to be synonyms, giving cross-references from the latter to 
the former. Thirdly, it cites the literature bearing upon the nomen¬ 
clature of each species, the bibliographic details being placed under the 
name now valid. Fourthly, it catalogues all the specimens of Blastoidea 
contained in the Geological Department of the British Museum (Natural 
History) at the time of writing (March, 1899). Lastly, it designates 
more particularly those among them that are of historical interest, as 
type-specimens or as having been figured, and supplies full references 
to the literature bearing on each individual specimen. Yet another 
purpose served by this method of compilation is that of a list of Blastoidea 
a Museo Britannico desiderata. 
The index to names is arranged in alphabetical order. All names, 
whether valid or invalid, are printed in the same heavy type, those of 
genera being in capitals. The names of species have the generic com¬ 
ponent printed at full length, so as to remove a possible source of error 
from those who wish to cut up the index for a slip-catalogue. Since 
every combination of names that has been suggested is given in this 
alphabetical series, it has not been thought necessary to encumber the 
volume with a separate index to trivial names only. The list includes a 
few names that are not now considered to belong to Blastoids, but which 
have been so considered at one time or another. 
The determination of certain names as valid, and the treatment of the 
rest as synonyma, was adopted for practical convenience. By this means 
the duplication, or even quadruplication, of references has been avoided, 
while all references to what is admittedly the same species have been 
brought under one heading. Since that heading can always be turned up 
from the cross-references, this introduction of personal opinion is a minor 
evil. In several instances ( e . g. species of Nucleocrinus and Orbitremites) 
the names here held to be valid may not be those familiar to users of 
recent writings on the Blastoidea. The changes are in accordance with 
the most widely accepted rules of nomenclature, and have been made only 
when the facts of the case are undisputed. An enthusiast for priority 
