SEA-FISHERIES LABORATORY. 205 



and 40,450 on November 2Tth, as against 11,400, the 

 highest number in these montlis in 1910. 



Rhizosolenia. — This important genus again had its 

 maximum in June, but did not reach so high a point as 

 in 1910. Notable hauls are 2,160,000 on May 22nd, 

 2,880,000 on May 29th, four hauls of from ^ to over 

 10 millions between June 3rd and 8th. The autumnal 

 increase this year did not amount to much, the largest 

 haul being 276.000 on October 19th. 



Thalassiosirn. — The spring maximum was again in 

 May, with 1,120.000 on May 29th. Quantities of several 

 hundred thousand per haul remained until June 5th, and 

 then the genus suddenly disappeared and was unrepre- 

 sented until October 5th, when 287,000 were taken in one 

 haul. 



Guinardia.- — This genus is very poorly represented 

 this year, the highest figure being 204,000 on June 1st, 

 compared with nearly nine millions the previous year. 



Lauderia. — This form also shows smaller numbers 

 than in 1910. The only haul of over a million was 

 1,203,500 on May 19th— whereas it attained to 20 

 millions in April, 1910. 



We add here the monthly averages of these seven 

 genera of Diatoms, as follows: — 



1911. Biddul- Chaeto- Coscino- Rhizoso- Thalassi- Guinardia. Lauderia. 



phia. ceras. discus. lenia. osira. 



Jan 31,758 11,903 5,119 64 22 



Feb 38,150 8,606 11,572 50 133 33 



March 124,225 41,990 73,796 1,425 283 160 



April 115,823 86,185 34,890 1,650 82 150 



May 21,139 22,745,683 17,531 858,208 217,329 27,938 312,363 



June 2,073 1,431,005 200 2,121,226 135,073 60,656 12,864 



July 478 7,180 551 



August ... 219 1,437 12 310 31 



Sept 11,110 868,017 1,479 21,018 481 1,511 



Oct 142,690 3,956,047 25,444 72,622 84,462 987 41,387 



Nov 341,231 143,251 17,402 12 2,597 12 



Dec 77,788 31,159 9,411 4 



