BULLETIN OF THE UNITED STATES FISH COMMISSION. 241 



of the liigb seas, actually tinge the surface when some of the highly- 

 colored forms are abundant. From the surface of the mid- Atlantic the 

 Challenger crew obtained stalked infusorians fixed to the shell of Spi- 

 rula, also an abundance of large radiolarians. Haeckel, Monograph of 

 the Eadiolaria, says the largest living Eadiolaria measure only a few 

 lines in diameter, but most of them are much smaller, and attain 

 scarcely a tenth, down to a twentieth of a line in diameter. At Saint 

 Jerome's Creek, Maryland, in an arm of the former, now used as an 

 oyster park, the writer found an abundance of a fresh- water Heliozoan, 

 not specifically distinguishable from Actinophrys sol. They were found 

 in great abundance at times on the surface of the slate collectors which 

 had been put down for the purpose of enabling the free-swimming fry 

 of the oyster to fix itself. This raises the question whether the fresh- 

 water protozoan fauna does not overlap the marine. The water in the 

 situation mentioned was not simply brackish, but positively salt. In the 

 same place great numbers of stalked and tube- or test- building ciliate 

 forms of Protozoa were also found. The magnificent bottle-green Freia 

 producta was found in the same locality in the greatest profusion. Some- 

 times several hundred might have been counted on a single square inch of 

 the surface of oyster shells, slates, or boards, giving such surfaces a dark- 

 greenish or speckled tint from their numbers. Very small species of 

 nudibranchiate mollusks {EoUs and Doris) were found creeping amongst 

 and over the forest of Protozoa, i)asturLng off of them. Amongst the 

 tubes of the Freia, and attached to them, a small operculate Cothurnia, 

 with a rich brown-colored test, was found in abundance, and, rarely, a 

 very curious form of Tititinnus, with a tubular, subulate test, to the 

 inside of which the stalk of the inhabitant was attached, at one side, 

 about half way up from its base. The open, or mouth, end of the per- 

 fectly hyaline test was very strongly toothed, or serrate. The species 

 may be named Tintinnus Fergusonii. Another species of Freia has been 

 detected, on the coast of New Jersey, by Professor Leidy, and, from a 

 verbal description given me by Dr. H. C. Evarts, a species occurs in the 

 ' vicinity of Beaufort, N. C. So abundant was Freia producta in Saint 

 Jerome's Creek that I apprehend that in its free-swimming young state, 

 previous to the time that it commenced to build its test, it afforded not 

 an inconsiderable proportion of food to the oysters planted in some 

 parts of those waters. Besides the Freia there were innumerable indi- 

 viduals of Vorticella observed. One of these had a very thick, brown- 

 ish cuticle ; but for numbers th<^se were again very greatly exceeded by 

 the compound stalked genera of bell-animalcules. Upon the very com- 

 mon alga, Laminaria, these were abundant, and upon the fronds of 

 another alga, the Grinnellia, in three or four fathoms of water, near the 

 middle of the Chesapeake, their number was truly astounding. In a 

 few such places where these algse were dredged up from the bottom, 

 covered with innumerable colonies of protozoans, it would doubtless be 

 much within bounds to state that there were 1,000 individual protozoan 

 Bull. U. S. F. C, 81 IG Api-ii S§, 1 8 82, 



