124 



Littoral furins: 



I'lndO-riis iirofurvntiiti Birge. 



Plcuro.rus (h-nticuhitiis Birge. 



Eiiri/ro'ciis lanuJlatKS O. F. M. 



Acropcnif! linrpae Baird. 

 The following genera were represented by at least one species each. 

 AIoiKi, (Ir(ii)tolebcris. and Simocciihalus. 



Ci/pris: and CordJird larviii were found in some of the catches. 



ROTIFERA. 



Fiiui- nirniliiTs of tliis group were specifically identified, Triarthra 

 li)Niiis(t(i. Ainirra cochleans, Ainirai a'-idrata, and Xotholcu louyispiiia. The 

 other niemlters of the group belonged to the genera AsphnifJnia, Polijarthra, 

 and Mdstifjoccrca. 



CHANGE IN QUANTITY OF PLANKTON. 



These oliservations covered too brief a period, July 10 to September 3, 

 to show much concerning the increase or decrease of the various plankton 

 coustitutents. In general, it may be said that there was comparatively 

 little change. There was apparently a slight increase of the phytoplank- 

 ton, due mainly to an increase of Clathrocystis. Only two forms of the 

 Crustacea showed any change. During August, there was a perceptible 

 increase of Diaptomus and Cyclops. They Avere found to be twice as 

 numerous the first of September as the last of July and first of August. 



DIURNAL MOVEMENT. 



Einschura locust lis. —This foi-m was not found regularly in the day 

 catches as it was present in only six of the twenty day series. On these 

 six occasions it was confined to the thermocline, that is. between five and 

 seven meters. It v.^as taken, however, in the surface catches of the six 

 night series. The time of its appearance at tlie surface varied from half 

 an hour to an hour and a half after sunset and it disappeared from the 

 surface about an hour before sunrise. In the all-night series of August 

 5-6, it was found in only one catch. This was at p. m.. five individuals 

 per 100 liters of surface water. In the all-night series -of August 27-28, 

 it reached a maxinuun of 14n per Kki liters at S p. m, 



