238 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



placed beside tliem, wliile with the other there were also introduced 

 iufusorial animalcules, the latter were much stronger, more active, and 

 thro"e better than the former." 



This appears to be very strong evidence in favor of the auimalcular 

 diet of these crustaceans. Other evidence, too, of quite as convincing 

 a character is not wanting. Those who have been in the habit of col- 

 lecting (piautities of microscopic material from ponds and ditches have 

 frequently observed very large schools of Entomostraca in such places 

 where the water as a rule is not absolutely stagnant, but where an 

 abundance of duck-weed, fresh-water alg;© of many kinds, as well as 

 various water plants of the higher orders make a splendid nidus for 

 all kinds of monads and ciliated and amoeboid Protozoa. These are the 

 Xilaces where Cyclops, Daphnia, and allies flourish inland in fresh water. 

 The writer has also noticed them particularly abundant in the wide 

 river flats near the mouth of the Susquehanna at Havre de Grace, where 

 there are large areas many acres in extent which are covered with a 

 liixuriaut growth of Potamogeton^ Anacliaris. and Vallisneria, making a 

 d«use mat of delicate stems and leaves upon which countless multi- 

 tudes of Protozoa may fix themselves and abide. If, in rowing through 

 such masses of aquatic vegetation, one will stop the boat and stir care- 

 fully among the plauts with the hand over the side and cautiously 

 w^atch the result, one will often notice that great n^^mbers of Entomo- 

 straca have been frightened from their leafy retreats. These are the 

 places where young shad ought to be liberated; in such idaces they 

 would find an abundance of food at an early period, or as soon as they 

 were fitted to partake of nutriment by swallowing. 



Just as we find the fresh water forms of Entomostraca take to the 

 shelter of aquatic vegetation at the mouths of rivers, so it appears that 

 many of the marine forms seek i)rotection, and probably food, under 

 cover of the fronds of marine algtie. Here is what their most recent 

 monographer says in relation to this point : '^A large number of species 

 haunt almost exclusively the forests of X^minfflr/fc which grow on rocky 

 coasts at and below low- water mark; the fronds of Laminar iasaccharina 

 in particuUir are the favorite abode of many species." (Brady, Monog., 

 Brit. Copep., Introd. I, p. 7.) Again, on page 9, he remarks, "The 

 washing of the fronds and roots of Laminarirc, which may be dragged 

 up by means of the hooked grapnels used on many coasts by kelp- 

 burners, often affords multitudes of Copepoda." 



They appear in many cases to be surface swimmers. I have myself 

 seen schools of several thousands of Daphniadw of a greenish yellow 

 color in the ditches south of Camden, N. J., swimming at the surface of 

 the water at midday in the bright sunlight. In the vicinity of Wood- 

 bury, in the same State, my friend, Mr. W. P. Seal, has taken great 

 numbers of a bright red-colored Coi>epod, apparently related to the genus 

 Pontella, and j>erhaiis undescribed. They were sufficiently abuudant 

 in some cases to impart a red tinge to the water. 



