Protozoa and Rotifera at Havana, III. 351 



the forms which, in the matter of food relations, bridge the 

 gap between plants and animals. Many of the smaller forms 

 like Metopidia, Colurus, Monostyla, and also Dinocharis and 

 Euchlanis are frequently found chewing the ends of fine fila- 

 mentous algae. At one time a Mastigocerca was observed 

 feeding on a piece of alga. It would puncture the outside, 

 and appropriate the immediate contents of a cell ; then it 

 would creep along, make another puncture, and continue its 

 meal. Diatoms also serve as food, and a Notliolca was found 

 that had its stomach crammed full of the rays of Asterio- 

 nella. Asplanchna priodonta and also A. brightwellii seem 

 to be omnivorous. I have frequently found Pediastrum, Vol- 

 vox, Codonella crater a, Difflugia globulosa, Anurcea tecta and 

 A. cochlearis in their stomachs. One Asplanchna herrickii 

 was observed that had just made a meal of two Brachionus 

 mllltaris; while an Asplanchnopus myrmeleo was found with 

 its stomach gorged with Chydorus. 



On the other hand, the larger species of Rotifera doubtless 

 form a considerable portion of the food of mollusks, min- 

 nows, buffalo fish, carp, suckers, and the like. Specimens of 

 Anurcea cochlearis were found in the stomach of a young 

 "croppie" and in that of a young catfish. It is possible that 

 the smaller Crustacea also live upon rotifers. This was es- 

 pecially indicated in Phelps Lake (substation F). There 

 were times when the water of this lake was swarming with 

 Entomostraca and the rotifers were very scarce, yet in a few 

 weeks there would be very few Entomostraca and a great 

 abundance of rotifers. Possibly the periodical disappearance 

 'of the rotifers was due to lack of food, but the disappearance of 

 the Crustacea seems explainable only on the supposition that 

 they depended on the rotifers for food. At one time a towing 

 was taken at this substation in which there was such an abun- 

 dance of Pediastrum — an element in the food of rotifers — that 

 the water was colored green, and in this same towing there 

 was an abundance of rotifers and very few Entomostraca. 



SEASONAL DISTRIBUTION. 



While our seasonal histories of the Protozoa show but 

 little tendency to a concentration in any particular part of 



