PRKFACi:. i\ 



Blastoidea, except the rare Pentephyllum and Eleutherocrinus, though the formertype 



is illustrated by a cast of the only known specimen, which belongs to the Museum of 

 the University of Dublin. As the National Collection also contains a good series of 

 the American Blastoids, and numerous representatives of those found in France, 

 Spain, Belgium, and Germany, together with the valuable collections made bj Rofe 

 and Gilbertson from the Carboniferous Limestone of Lancashire and Yorkshire, we 

 have no hesitation in saying that it is not only unrivalled, but that it is not likely 

 ever to be surpassed in the completeness of its collection of Blastoidea. For the 

 localities where Hole and Gilbertson obtained their specimens are no longer so pro- 

 ductive as they were, and neither Blastoids nor Crinoids can now be procured so easily 

 as was the case even up to twenty years ago. 



We have further specially to acknowledge the generous aid which has been 

 afforded to us by the Council of the Royal Society, who placed at our disposal in 

 1881 a sum of money from the Government Grant Fund, to assist us in adequately 

 illustrating our work ; we are also indebted to them for allowing the sixteen Plates 

 which had been paid for out of that fund to be published in a volume issued by 

 the Trustees of the British Museum. These Plates, together with the four which 

 have been since drawn, are the work of our friends, Messrs. Charles Berjeau, 

 F.L.S., and Percy Highley ; and we find it difficult to express our appreciation 

 of the care and zeal with which they have performed a very important share of our 

 joint work. 



The arrangement of the Plates has been necessitated by circumstances. The 

 material which is now at our disposal was not all in our hands when the earlier 

 Plates were drawn, but has reached us at intervals during the progress of our 

 researches ; and the consequence is that the figures illustrating some specific forms 

 are scattered over several Plates, instead of being concentrated on one or two. as 

 they would have been had we been able to collect all our material before com- 

 mencing our illustrations. 



"We have endeavoured, so far as it has been in our power, to make the present 

 work a monograph of all described Blastoidea ; but we have found ourselves obliged 

 to leave it incomplete at many points. There are very few European Blastoids, pro- 

 bably not half a dozen in all, which we have not studied ; and by the kindness of 

 Mr. Wachsmuth and of other friends in America we have been enabled to examine 

 one or more species of all the genera which occur in that country. But there are still 

 many species about which little is known. In some cases this is due to the rarity 

 of the literature concerning them, and in others to the want of adequate descriptions 

 or figures. In many cases, too, we are in great uncertainty as to the stratigraphical 

 position of a species, owing to a want of precision or of accurate geological infor- 

 mation on the part of its describer. These are questions which <an only be satisfac- 

 torily solved on the spot, and we must therefore leave them in the hands of our 



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