List of Diatomaceae from a deep-sea dredging in the Atlantic Ocean off Delaware Bay by the U. S. Fish Commission steamer Albatross

LIST OF DIATOMACEiE FROM A DEEP-SEA DREDGING IN THE ATLANTIC OCEAN OFF DELAWARE BAY BY THE U. S. FISH COMMISSION STEAMER ALBATROSS. BY Albert Mann. In presenting this list of sj)ecies of the Diatomacenp, accompanied with mounted specimens, which I have discovered in the first of the deep-sea Atlantic dredgings submitted to me for examination, I wish to oflFer some general results of the investigation. This dredging was taken by the United States steamer Albatross at Station No. 2721, being in latitude 38° 56' 00" N. and longitude 72© 11' 30" W., and in 813 fathoms of water. The species found (numbering 145, and with varieties 150) comprise not only marine forms, but a large number that are known to be fresh-water, and some found hitherto only in a fossil state. Before treating the material with acids I carefully examined it as it was sent to me, i>reserved in alcohol, and discovered that none of the frustules contain a particle of endochrome or organic inatter. This, taken in connection with the depth of water, the large number of species represented, and the before-mentioned fact that tliere are many fresh-water and fossil as well as marine forms, makes it evident that the entire deposit is (composed of fine detritus gradually sifted down upon the sea bottom and conveyed there by currents from a considerable distance. The Delaware Eiver has without doubt supplied most of the mate-rial of this dredging, as it empties into the ocean almost directly west of the locality where it was taken, and as most of the forms (marine and fresh) are such as are common in rivers and streams of correspond-ingly temperate latitude. An interesting corroboration of this is to be found in one of the fossil species, Navicula Schultsei Kain. This diatom was originally discovered in material from an artesian well at Atlantic City, N. J,, at a depth of 406 feet, by Mr. C. H. Kain, of Pliiladelphia, Pa., and named by him. The same stratum however, outcrops at several places along the Delaware River watershed, notably at Shiloh, N. J., and this diatom, with, perha])s, Raplioneis gemmifcra Bhrb., and Dthcr of the fossil forms, could have gotten into this dredging in no other way than by being brought by the Delaware River from some of these outcrops. But there are some forms occurring abundantly in this deposit which are essentially tropical ; these Proceedings National Museum, Vol. XVI— No. 937. 203

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List of Diatomaceae from a deep-sea dredging in the Atlantic Ocean off Delaware Bay by the U. S. Fish Commission steamer Albatross

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