55 

 PROTOZOA. 



The extreme smallness of some of these forms and the con- 

 sequent difficulty in identifying them have made it necessary to 

 leave many of them unidentified. Exceptions were made in the 

 case of a few very distinctive or commonly occurring species. 



The numbers of Protozoa in the samples almost reach the 

 500 line per 50 cc. in July, at other times varying between 25 

 and 125 per 50 cc. These numbers, too, are no doubt abnormal. 

 The appearance of the chief species is recorded in Table I. They 

 belong for the most part to the Infusoria. A single Silico- 

 flagellate, Distephanus speculum appeared from time to time, and 

 a Flagellate, Dinobryon sertularia, occurred very rarely. 



ALGAE. 



The Chrorophyceae were represented most frequently by 

 Anhistrodesmus falcatus, which appeared in small numbers at 

 irregular intervals, and rather more frequently in May. 



Protococcus sp. occurred rarely, as did a species of filamentous 

 green alga, possibly Microspora sp. 



The C yanophyceae were represented on two or three occasions 

 by short chams of OsciUatoria sp, 



METAZOA. 



It is evident that almost the whole of the Metazoan portion 

 of the plankton is prevented from entering the tanks, as only 

 odd specimens appear here and there in the records. 



Conclusion. — It will be apparent from the foregoing account 

 that an investigation of this kind cannot be carried on satisfactorily 

 by the use of the supply tanks of the Laboratory as a source 

 of the samples, but will have to be done by means of water samples 

 or tow-nettings from the open sea, or preferably by both methods 

 used simultaneously. Large species fail to gain admittance to 

 the tanks, Dinoflagellates are able to multiply too rapidly in the 

 tanks throughout the year, and Diatoms evidently succeed in 

 reproducing too copiously during the early part of the year to 



