150 HABITS AND ECONOMY OF THE MOLLUSCA. 



coast are destitute of limestone, but abound in shell-banks which 

 may be burned into lime ; or in shell-sand, for the use of farmers. 

 The taste for collecting shells and competition among collectors 

 have caused some of the rarer species to be valued at extraordi- 

 nary prices, which usually tend to diminish as the formerly little- 

 frequented regions which they inhabit become better explored. 

 The extravagant rates that have been given for rare shells are 

 less to be regretted, since they have induced voyagers to collect 

 them. Mere shell-collecting, however, is no more scientific than 

 pigeon-fancying, or the study of old china. For educational 

 purposes the best shells are the types of genera, those which 

 illustrate particular points of structure ; and, fortunately for 

 students, excellent generic suites can be obtained for very 

 reasonable prices. Not only have well-named private collections 

 largely increased in number during late years, but almost every 

 college museum includes what would formerly have been 

 considered a large conchological cabinet. The three largest 

 conchological collections in the world are those of the Academy 

 of Natural Sciences of Philadelphia, the British Museum, and 

 the Museum of Natural History at Paris. The first-named 

 includes about 140,000 specimens, all mounted and labeled, 

 contained in about 35,000 trays ; its geographical suites are the 

 most extensive known. The British Museum collection is about 

 half or less than half as large as that of the Philadelphia 

 Academy, but contains manj^ more specific types, inasmuch as 

 it includes the famous Cumingian Collection. A large majority of 

 these types are not good species ; nevertheless they have a value 

 as evidence that their described distinctive characters are value- 

 less.* The Paris collection is, perhaps, the smallest, but its 



* "No one knew better than Mr. Cuming the value of a new name to 

 his specimens, as shown by his enmity to any one who doubted the novelty 

 of the species described. He would not allow me to see his collection for 

 many years after his return from South America, because I had pointed 

 out to him at one of the meetings of this society that some of the shells 

 which Messrs. Sowerby and Broderip had described as new were well- 

 known species, and -well tigured by Chemnitz.' " Since that period Mr. 

 Cuming refused a well known conchologist, who had previously described 

 several shells from his cabinet, any further use of his collection, because 

 he refused to admit that certain specimens which he sent to him to be 

 described were new to science, or different from species already described. 

 The system that Mr. Cuming adopted of selecting three specimens of 

 each variety or species most alike, tended to prevent the number of nominal 

 or presumed species fi-om being observed during a casual examination of the 

 collection, as it excluded those specimens which showed the transition 

 from one variety to another, which occurs in any given species— more 

 especially as the species were not arranged in the drawers so that the most 

 allied of presumed species were near to each other, but, on the contrary, 

 they * * * were often placed in distant parts of the series." — Dr. J. E. 

 Gray, Zool.Proc, 729, 1867. 



