r 



244 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



ently Podophrya quadripartita. Of marine forms, I have seen but two 

 that I could regard as distinct from each other; the one, a vQry common 

 form, is the old and well-known Acineta tuberosa of Ehrenberg, with two 

 clusters of suckers. This form I have frequently seen with diatoms 

 which it had seized and from which it was abstracting nutriment. The 

 other form was much larger than the preceding and appears to be iden- 

 tical with the species described under the name Podophrya gemmipara 

 by Hertwig. It has the same robust stalk, with the same close tran. 

 verse annular markings, the same taper, and is similar in the form of 

 the tentacles, which are often irregularly beaded or swollen. I was en- 

 abled 4o observe in part its development, which is also similar to that 

 of the Helgoland species of the North Sea above mentioned. They were 

 found in great abundance on the surface of the fronds of Laminaria, 

 together with the Acineta tuberosa; not as abundantly, of course, as 

 the Zodthamnium, but in sufficient numbers to make them a very con- 

 siderable factor in the protozoan life found in the vicinit}' of New Point 

 Comfort. 



The majority of the free j^rotozoa and many monads, such as Nocti- 

 luea, have scarcely been considered, but enough has been said, I think, 

 to give some idea of the actual importance of the minute animal and 

 vegetable life of the sea to make it clear that there is a most intimate 

 relation of dependence existing between the lowest and the inteniio- 

 diate forms of life. Why is it, for example, that we should find the 

 Copepoda so abundant among the Laminar ia along the sea-coast? Have 

 we not shown that on the fronds of these algae there exists, in most 

 instances, almost a forest of protozoan life, upon which these creatures 

 may be supposed to pasture"? We do not find the Laminaria itself 

 eaten. Again, the foraminiferal and radiolarian fauna of the high seas 

 appears to be, in great measure, a surface fauna, according to the evi- 

 dence of a number of investigators. This fact appears to have an im- 

 portant relation to the vast shoals of Cope])oda observed at the surface 

 of the sea by various naturalists and expeditions. It is not to be sup- 

 posed, however, from what has been said, that the Copepoda are the 

 only consumers of this vast array of individual protozoa. Cross- sec- 

 tions through the oyster, which the writer has prepared and mounted, 

 show the tests of various genera and sx)ecies of diatoms mixed among 

 the indigestible earthy matters and sediment which has been swallowed 

 along with the food. It is i^robable that the oyster swallows and digests 

 many of its own embryos, and not improbably many embryos of such 

 forms as Bryozoa and sponges, besides the diatoms, desmids, and proto- 

 zoa which make up the most of its food. Ordinarily the contents of 

 the stomach of the oyster are too much disorganized to learn much 

 about what it has recently swallowed, hence we are at a great loss to 

 know just exactly of what all of its food consists; just so with the 

 Copepoda — they themselves are doubtless eaten by other Crustacea, 

 these in turn by others. We saw that Doris and Eolis jDastured upon 



