SHELL COLLECTION IN THE AMERICAN MUSEUM 



By L. P. Gratacap 



PERHAPS no department of zoology 

 exceeds conchology in appeal to the 

 imagination and to the intellect. 

 Shells are among the earliest evi- 

 dences of life upon our globe and their pre- 

 servation in the older rocks surpasses in its 

 intelligibility that of any other order of or- 

 ganisms, while in the world around us they 

 inhabit the land and the sea with a univer- 

 sality of diffusion that is preeminent. 



Their formal contrasts are also remarkable. 

 Grouped to-day under Mollusca, the zoolo- 

 gist contemplates an assemblage of animals 

 which in their divergent aspects at either end 

 of the series brings him in contact with the 

 extraordinary calamaries, squids and cuttle- 

 fish and with the graceful, delicately colored 

 and fragile nudibranchs. No systematic 

 division of the kingdom of living things per- 

 haps offers so apparently heterogeneous an 

 association. Let the reader recall to mind 

 those marine monsters of fabled ferocity such 

 as the giant squids, creatures that may have 

 attained a length of fifty feet, a great part of 

 which belonged to their grotesque and power- 

 ful arms, then watch — if he is afforded the 

 pleasure — the nereid-like beauty and pro- 

 tean coloration of Dendronatus as he may see 

 it on rocky bottoms or in tide pools on 

 the coast of Maine, and then bring together 

 under one collocation these almost irre- 

 concilable elements and he will realize the 

 wonderful contents of this study; all the 

 more too as in neither the squid nor in the 

 sea-slugs is there any showing of a shell. It 

 is indeed not possible to reserve astonishment 

 when we find the bivalve (oyster, clam, 

 mussel), united in the same class with the 

 big whelks {Stromhus), the colossal tritons 

 and the variegated cowries {Cyprcea) and also 

 with those singular sluggish patches of many- 

 plated elliptical bodies immovably adherent 

 to rocks, which the fishermen call "coats-of- 

 mail," and collectors call "chitons," and 

 which the nomenclatural facility of syste- 

 matists arranges under the descriptive desig- 

 nation of the Polyplacophora. 



Turning to the land the student encounters 

 an innumerable army of moUuscan inhabi-- 

 tants which, excepting that they do not fly, 

 fill it at all points, not omitting its lakes and 



rivers and which take on in southern climes 

 the most vivid colorations. 



The interest of shells however is not at all 

 limited to these contrasts of form or function 

 or to their diversity of ornamentation. By 

 reason of their distribution in time they allow 

 the palaeontologist to guide or correct the geol- 

 ogist, while almost more discernibly than any 

 other kind of life, they mark the evolutionary 

 stages of creation, and enable the student of 

 past conditions to determine the geographical 

 and climatic fluctuations of the continents. 

 They notably contribute to the current dis- 

 cussions which engage naturalists as to centers 

 of radiation, convergence, or parallelism of 

 growth, survival, selection, migration, varia- 

 tion, rudimentary organs, environment, ac- 

 celeration and heterostylism, and while they 

 may lack what might be called a muscularity 

 of demonstration, their evidence perhaps is 

 more conclusive if more subtle, than that 

 derived from the mammals or the birds or 

 the reptiles. 



The shell collection now opened to the 

 public, after three years of seclusion, by no 

 means illustrates all the claims made above. 

 It is primarily a collection of living shells and 

 the shadowy extension of the class backward 

 to the first dawn of life is scarcely hinted at. 

 Nor at present has it been made illustrative 

 of the ecological problems which exercise so 

 much fascination for investigators, problems 

 of where and how and why. In the condi- 

 tion in which the visitor will find it, it is 

 a fairly representative collection of marine, 

 fresh-water and land shells, and only in the 

 synoptical series on the south wall, is any 

 intimation gleaned of the existence of mol- 

 luscs which have no shell, such as the squids 

 and nudibranchs. But the collection is not 

 on that account deprived of interest or charm, 

 indeed a too preponderant invasion of fossil 

 shells would prove deterrent to the average 

 visitor and the shell-less molluscs could only 

 secure representation, as they do, in alco- 

 holic specimens or by models. 



The apportionment of parts in the hall is 

 quickly explained. The flat table cases at 

 the north and south ends contain land shells, 

 with a representation of brackish water shells 

 {Cassidulus, Pythia, Melampus) and a few 



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