242 REPORT — 1856. 



series was obtained by repeated processes of elimination, from the examina- 

 tion of about 11,000 specimens. The whole number of shells passed under 

 review probably exceeded 100,000. The following was found to be the most 

 satisfactory plan for the determination of specific limits: — (1) to spread out 

 the entire mass in somewhat of order before the view, in order that the gene- 

 ral idea of the species (so to speak) might be received by the mind ; (2) to 

 examine the specimens one by one, in comparison with an ordinary shell 

 selected as a standard, putting to one side all that for any cause attracted 

 attention ; (3) from the hundreds thus selected out of the thousands, or the 

 scores out of the hundreds, to arrange series according to observed differences; 

 (4<) to subject these to a rigid scrutiny with each other and with neighbour- 

 ing species ; (5) to make a selection that should exhibit not extremes only, 

 but intermediate grades ; and (6) to write the description while the result 

 of the previous processes was fresh in the recollection. No observations, 

 indeed, can compare for accuracy with those made on living animals in their 

 native haunts ; but the next best process is the examination of large num- 

 bers of specimens, such as the almost exhaustive diligence of M. Reigen has 

 placed at our disposal. The process may require considerable time and no 

 small amount of patience; but results thus obtained are far more satisfactory 

 than the plan too often followed, of picking out a few specimens of leading 

 forms, which alone are available to naturalists for description. So marvelous 

 indeed are the variations of growth thus traced to the same specific source, 

 that we may well accept with doubt species that are constituted from very 

 limited materials. This caution is by no means to be overlooked in using 

 the very catalogue in question ; as the only materials for a knowledge of the 

 small species (which amount to no fewer than 314 out of 691) were the dirt 

 obtained from the washings of the shells, which had most fortunately been 

 sent "in the rough;" and the fragments obtained in ransacking the backs 

 of a few Spondi/U, which were most obligingly placed at my disposal by 

 R. D. Darbishire, Esq., of Manchester, who had succeeded in rescuing them 

 from the publican's " museum."* 



It would of course have been far more satisfactory, for the purposes of 

 science, had the collection never passed through a dealer's hands. The 

 fortunate circumstance, however, of its size and value requiring a room to 

 be emptied and kept locked for its custody, has prevented the chances of 

 error which would otherwise have crept in. No species are inserted in the 

 catalogue but what were obtained from the boxes in this room, and from the 

 large shells about the parasites of which there can be no mistake ; except 

 Ficula decussata, of which Mr. Hanley distinctly remembers the appearance 

 of a very few specimens in the Havre collection. This, which, though com- 

 paratively small, filled twenty-eight boxes, after lying some time in France 

 without a purchaser, was in the main sent to London, and disposed of in lots 

 at the auctions, mixed with other shells, and without any knowledge being 

 communicated as to their history. They have been freely distributed as 

 though from Panama ; and several of them appear in the British Museum, 



labelled "Australia, presented by Metcalf, Esq." Several freshwater 



shells, Cyrenm and Ampullarice, are believed to have come from this source; 

 but there was no trace of them in the Liverpool collection. In general, the 

 two sets so far agreed as to make it probable that the species were divided. 

 Messrs. Lizardi received a list, in which the exact localities of all the shells 



* I am under the greatest obligations to Mr. Darbishire for his valuable aid from the com- 

 mencement of the work. We alone were admitted by Mr. Hulse into his secret chamber, filled 

 with the unmixed spoils of the Mazatlan waters ; nor should I have ventured to pursue this 

 inquiry, which would have been conducted far better under his auspices, had not professional 

 engagements entirely prevented his devoting the time necessary for such a purpose. 





