SEA-FISHERIES LABORATORY. 159 



The greatest Diatom catches are as follows : — 



Coscinodiscus — 225,630 on March 22nd. 



Biddulphia = 580,000 on April 20th. 



Lauderia = 1,140,000 on May 11th. 



Thalassiosira = 1,890,000 on May 17th. 



Chaetoceras = 10,741,000 on May 17th (5,967,000 

 on September 23rd). 



Rhizosolenia = 64,295,000 on May 24th. 



Guinardia = 1,036,000 on June 14th. 



In all cases this year the autumn increase is much smaller than 



the spring maximum. 



Reviewing the records of the six most abundant Copepoda 

 shows that most of them have their maxima late this year — 

 Acartia in June, Temora in July, Calanus and Oithona in 

 August, Pseudocalanus in September and Paracalanus in 

 November. The largest individual haul was 122,000 Pseudo- 

 calanus elongatus on September 27th. There were about 

 98,000 Oithona on November 11th and over 10,000 Paracalanus 

 on the same date. On the whole Copepoda were abundant 

 later in the year than in 1919. 



Noctiluca was present from August on to the end of the 

 year, but only reached about 10,000 in a haul — in contrast 

 to over 26,000 in July last year. 



Echinoderm larvae were fairly abundant, up to over 

 9,000, at various dates from March to September. Sagitta 

 was most abundant in June and July, rare in other months, 

 though a few are always present. Polychaet larvae were 

 present throughout the year, but most abundant in the early 

 months, up to 56,000 on March 4th. Molluscan larvae, both 

 Gastropod and Lamellibranch, have also much the same dis- 

 tribution, but only reach the thousands in early spring and 

 again in late autumn. Oikopleura was present throughout the 

 year, being most abundant in the warmer months and reaching 

 12,000 in May and 17,000 at the end of September. In most 



