CHITONS, THEIR COLLECTION AND PRESERVATION 



By S. Stillman Berry 

 Reprinted from MoUusca, Vol. 1, No. 7, 1945 



The curious assemblage of mollusks known as Cradle-shells, Chitons 

 or Coat-of-mail Shells holds a particular interest for the student of West 

 American marine fauna, since the group there attains a development in 

 genera and species without parallel save only in Australian waters. 



They evince a surprising specificity of habit, and each is rarely, if ever, 

 found outside its own peculiar station. Some species and even genera, for 

 example, are successfully looked for only in the hollows and crannies of 

 rough boulders in the mid-tidal area; some affect the shallow pools which 

 on a rocky shore become accessible to the collector long before the tide has 

 reached its ebb; others occur crowded amongst the mussels and barnacles 

 on jutting headlands exposed to the full power of the surf, while yet others 

 are found only under rocks or in their deepest crevices. 



Sandy beaches a'"e generally quite barren of these animals, although 

 one of our species, the giant Cryptochiton, occasionally occurs there. Many 

 kinds are to be obtained only from deep water, in quite restricted areas, as 

 in Monterey Bay, where my repeated hauls were quite in vain for several 

 species outside the precincts of a certain bank of hard blue clay, its angular 

 crags often covered by an incrusting sponge of a purplish-rose color not 

 unlike that prevailing amongst several of the chitons found in numbers on 

 such of its fragments as are broken oflF and brought up by the dredge. Some 

 species are found only at the lowest tides or dredged below tide-mark; 

 others found at such tides are hardly ever dredged; some are very common 

 in the dredge hauls as juveniles (e.g., Tonicella) but the adults all seem 

 to have moved ashore. One interesting and not too well understood species 

 (Cyanoplax loivei) is hardly known to us except for its frequent occurrence 

 in large kelp holdfasts torn free by storms and cast on shore. On the other 

 hand the zone of such forms as the related C. hartwegii and most of Nut- 

 tallina is left behind in the retreat of even a moderate tide. Several remark- 

 able and astonishing Australian species of Stenochiton are found only on 

 certain marine plants such as the eel-grass. No forms analogous to those 

 have as yet been discovered in our waters. None the less, wherever a 

 collector may find himself, he will do well, if he wishes to be sure of obtain- 

 ing a complete representation of the fauna, to give every possible type of 

 location or habitat which his locality affords an exhaustive search. 



On some rocky strands an especially useful method of collecting is to 

 wade out in bathing garb at the lowest tides and lift out rocks of manage- 

 able size from as far under water as one can extricate them, bringing them 

 in to shore for examination. Quite rare species or even now and then the 

 great prize of an undescribed one will sometimes be brought to light in 

 this way. 



On our coast at any rate we may safely generalize that the most 

 favorable area for chitons is from just above the low- tide line to perhaps 



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