THE MUSEUM. 



249 



is here an appeal to the eye that may 

 better the heart. 



In the inimitable ages of the past, — 

 we know not when, — but, at all 

 events, while the Stone Lillies were 

 carpeting the quiet sea with their 

 growth, and many species of Shark 

 were disporting in the water, there 

 was, even then, the pencil and en- 

 graving tool, guided by the Invisible 

 and Divine Hand, at work in these 

 silent recesses, to paint and hew. 



While there is nothing very strange 

 in the occurrence of this mineral here, 

 because the geographical distribution 

 of the Nickel ores is rather general, 

 there are still some things to note. 

 Not only in ones own Country but 

 also in foreign localities, Nickel is 

 very apt to occur with Chrome ore. 

 And both in connection with Serpen- 

 tine rock. It does not occur so here. 

 Nor, except some Magnesian lime- 

 stone in places, is there any rock akin 

 in Chemical constitution, in lots or in 

 part, to Serpentine. And certainly 

 Chromium is wanting, though the Sul- 

 phide of Iron and Copper are, in some 

 places, present in sufficient quantity 

 to give irised coloring to the Calcite. 

 It is to be noted all these metals occur 

 as Sulphides, and hence changed from 

 their primitive condition and brought 

 to this state by .the deoxidizing action 

 of decaying animal matter, which was 

 abundant at that age, if we may judge 

 from the fossil remains. Lacking the 

 association of the Chromite and Ser- 

 pentine rocks of other localities, how- 

 ever, it stands alone here as the only 

 Nickel ore unaccompanied by "Emer- 

 ald Nickel," which seems to result 

 from infiltration under such circum- 

 stances. Geo. M. Crofts, 



Summitville, Iowa. 



The Collection and Preservation 

 of Marine Invertebrates. 



Classification. 



The animals inhabiting the sea, ex- 

 cluding the fishes and other verte- 

 brates, may be divided, for conven- 

 ience, into groups, as follows: ist 

 Crustaceans, including crabs, hermit 

 or soldier crabs, lobsters, langoustes, 

 cray-fish, cavicroiics, shrimps, prawns, 

 sand-hoppeis, beach-fleas, whale-lice, 

 sea-creepers, pill-balls, fish-lice, sea- 

 spiders, water-fleas, gill-suckers, and 

 other parasites on fish, also barnacles. 

 2d. Annelids, including all kinds of 

 sea-worms, some of which hide among 

 seaweed and pebbles, but most of 

 which live in mud or sand, many hav- 

 ing tubes. 3d. Cephalopods, or cut- 

 tle-fishes and squids. 4th. Naked 

 Molluscs, or sea-slugs. 5th. Shells, 

 both bivalve and univalve. 6th, 

 Tunicates, vulgarly called "sea- 

 squirts," con?isting simply of leathery 

 balls or sacks of various shapes, with 

 two apertures, often occurring in com- 

 pound forms. /th. Bryozoans, or 

 those minute coral-like incrustations 

 found on seaweeds, stones, and old 

 shells. 8th. Holothurians, those 

 worm-like of slug-like echinoderms 

 like the bichele-mer or trepang. 9th. 

 Echini, sea-eggs or sea-urchins, most 

 of which resemble chestnut burrs, 

 being covered with spines. loth. 

 Asterias and star-fish of all kind, iith 

 Polyps, including corals and corallines, 

 and those minute animals from which 

 the medusae are developed. And 12th. 

 Sponges. 



Localities and Stations. 

 Where the retreat of the tide is suf- 

 ficient, the sea-shore always affords 

 the best field for the collector, and the 



