IV. PREFACE 



tablet in the Catalogue, Of the minute specimens, magnified 

 sketches are given, drawn under the microscope with Chevalier's 

 prism-disc. The principal part of the money required for the 

 purchase of the shells has been generously and without solici- 

 tation provided by Herbert Thomas, Esq. of Bristol. For the 

 remainder, and for all the work, from the first sorting and wash- 

 ing to the permanent allocation, (including no inconsiderable 

 ?=hare in the manual labour of printing,) I am alone responsible. 



The duty of writing the Catalogue was intrusted to me by 

 Dr. Gray. I was ill fitted for it, (1) by almost entire ignorance 

 of conchological literature, and (2) by living in a country town, 

 with extremely limited access to scientific books and collections. 

 There did not appear however any competent naturalist who 

 possessed the absolute essentials of time and full access to the 

 Mazatlan materials. I therefore undertook the task, trusting 

 that its acknowledged deficiencies might in some measure be 

 compensated-for by great patience and care in the faithful use 

 of those means of information which were within my reach.* 

 I have endeavoured to make it a companion to Prof. C. B. Ad- 

 ams' extremely valuable Catalogue of the Shells of Panama, 

 which belong to the same great Tropical Fauna of W. America. 



An estimate of the value of the Iteigen Collection as a 

 geographical authority, and a comparison of it with other 

 neighbouring faunas, will be found in the "Report of the pre- 

 sent state of our knowledge of the Mollusca of the West Coast 

 of N. America" presented to the British Association in Sept. 

 1856, and published in its transactions, pp. 159 et seq. The 



* In the course of the inquiry, I have met with the greatest kindness from 

 naturalists, most of whom were previously unknown to me, but to whom I 

 applied for assistance. To Hugh Cuming, Esq. I am under extraordinary obli- 

 gations for his singular urbanity, in allowing the unrestricted use of his invalu- 

 able collections, his library, and his original information to a complete stranger. 

 Dr. A. A. Gould, of Boston, U. S. intrusted to my care, and to the perils of the 

 Atlantic, the whole of his collections and notes from the W. American coast, for 

 comparison with those known in this country. To Dr. Gray and R. M' Andrew, 

 Esq. I am indebted for the long use of valuable works, and for advice and assist- 

 ance throughout. Prof. Dr. Dunker, of Marburg, gave me valuable aid in the 

 Mytilidae, J. D. Gaskoin, Esq. in the Cyprseadse and Columbellidse, L. Reeve, Esq. 

 in the Patellidae, W. Clark, Esq. and W. Bean, Esq. in the Cajcidae, J ."Alder, Esq. 

 in that family an^d in Jeffreysiadse, and Miss Steere in Olividse. S. Hanley, Esq. 

 allowed me the use of his collection, (representing the Havre division of M. 

 Reigen's stores,) and, along with R. D. Darbishire, Esq. Dr. Baird, Messrs. 

 H. & A. Adams, Rev. T. Hincks, S. P. Woodward, Esq. and F. Archer, Esq. 

 gave the benefit of critical judgment and experience whenever solicited. I am 

 also under great obligations to the officers of various public museums and 

 libraries, for the kindness with which they have attended to my requests. One 

 whose promised aid would have been of invaluable service, and whose friendly 

 encouragement mainly induced me to undertake the work, was, at its com- 

 mencement, suddenly removed from the field of labour which was opening before 

 him with such promise in the metropolitan university of Scotland. 



