x PREFACE. 
from the Wenlock series, which has been purchased by the University since Prof. M°Coy’s 
Catalogue was printed—all these additions prove the necessity of corresponding changes in 
our Paleozoic Catalogues. 
After Mr Salter had left the service of the Government Survey he several times visited 
me at Cambridge, and was desirous to do his best to supply the imperfections of our 
Catalogue; and I joyfully accepted his offered services, knowing his great skill as a Natural 
Science Artist, and believing him, after his long-tried labours under the Government 
Survey, to be unrivalled in his exact scientific knowledge of the fossil Invertebrata of the 
British Isles. One condition of his engagement was that his work should be constructed 
as a Supplement to the old Catalogue, and not as an independent work. This condition Mr 
Salter professed to accept, though as his labours advanced he did not by any means 
perfectly conform to it. 
To his personal applications, seldom communicated to myself, and to the knowledge that 
he was employed in completing a Cambridge Paleozoic Catalogue, we owe many of the 
additions to our older Paleozoic Collection, to which I have before alluded. And let me 
here record in behalf of the University my grateful thanks to the Earl of Ducie, to David 
Homfray, Esq. of Portmadoc, to Dr Hicks of St Davids, to Mr Lightbody of Ludlow, to 
Mr Ash, and to Mr J. Plant of the Royal Museum, Salford, for their generous donations 
to our Collection; and I trust that the several donors have found a grateful and respectful 
notice in Mr Salter’s pages. If the names of any other benefactors have been here omitted, 
I can only plead in my behalf the death of Mr Salter before the Catalogue was quite 
complete, my present infirmity of sight which prevents me from consulting my Journals and 
Memoranda, and the strange clouds of oblivion which too often trouble an old man’s memory. 
Mr Salter’s task advanced very slowly; for his bodily health and his nervous system 
seemed to have been almost broken up by the stress of hard mental labour which 
had been imposed upon him through many preceding years. On several occasions he aban- 
doned his task at Cambridge, and went to recruit his health by a residence of a few 
months at Malvern, where he remained under medical care. But still the work did 
advance in spite of these interruptions, and the University at length undertook to pay 
the cost of it under certain conditions, with which he was willing to comply. 
After many delays and much anxiety (and I may add after much personal cost to 
myself) Mr Salter’s manuscript took a form which made it fit for the press. I do not 
however think it would ever have reached that state but for the kind advice and en- 
couragement and judicious help given to its author by the Master of St Peter’s College. 
And after the first press-work was done, it still was evident that the Catalogue required 
careful revision and correction; not in the naming and description of the species, but in 
