SEA-FISHERIES LABORATORY. 375 



June. It was then entirely absent from our nets (except 

 in one haul on September 11th, when 50 were taken) until 

 November 1st, and the highest record from then till the 

 end of the year was under 14,000. 



Rhizosolenia. — Leaving out of account the abnormally 

 high records for Rhizosolenia in 1912, our numbers for the 

 spring and summer of 1913 agree fairly well with former 

 years. It is represented by occasional hundreds only until 

 April, when we get a few thousands ; it reaches 706,000 on 

 May 16th, 5,176,000 on June 14th, but the actual maximum 

 is this year in July, not June, with 8,258,000, on the 24th. 

 The numbers then fall to a few tens by the beginning of 

 September, rise to 19,500 on September 18th, and fall 

 again to zero by the middle of October. The genus is only 

 represented on four occasions from November 25th till the 

 end of the year. 



Thalassiosira. — The maximum was, as in most years, 

 in May, with 6,580,000 on the 16th, but on no other 

 occasion did the numbers reach the millions. The genus 

 had disappeared by June 17th, and there was no autumn 

 increase, only one haul from that date to the end of the 

 year containing any specimens at all (viz., November 29th, 

 with 50). 



Gidnardia. — The numbers this year are not so high 

 as in 1912, but are much higher than in 1911. They begin 

 to increase towards the end of March, reach six figures on 

 two dates in May, and seven figures on six occasions from 

 June 11th to July 8th, the latter date having the maximum 

 of 2,260,000, but the highest monthly average is June, 

 with 945,387. The numbers then decrease steadily to zero 

 on August 7th. There is a low autumnal maximum of 

 27,000 on September 22nd, and from then till the end of 

 the year the genus is usually represented, but by nothing 

 higher than 1,400. 



