188 PROF. W. A. HERDMAN ON THE DISTRIBUTION 
The folowing table showing the largest hauls of total Diatoms and 
of total Copepoda in each of the ten years brings out well how greatly the 
Diatoms outnumber the Copepoda—in some cases in the proportion of about 
a thousand to one. 
Diatoms. Copepoda. 
a | EIUS 
| Largest haul. | ^ Date. Largest haul. | Date. 
1907 ....| 698,950 | April 6th 28,900 | Aug. 17th | 
1908 ....| 5,746,300 May 28th 68,015 | Sept. 14th 
1909/52: 10,358,300 April 22nd 71,010 | Oct. 18th 
1910 .... 70,128,400 | April 22nd 119,650 | Sept. 19th 
1911 ....| 69,982,500 | May 16th 948045 | July 18th 
1919 ....| 202,993,600 | May 30th 223,789* | May 20th 
1913 ....| 205,814,700 | May 16th 118600 | July 21st 
1914 ....| 155,288,000 ^ May 4th 217,571 | Nov. 9th 
1015.29 18,895,500 June 15th 117,940 | Aug. 2nd 
1018 2 -| 24,260,800 May 25th 118,524 | Sept. 25th | 
wW o 64,339,250 | May 3rd | 147,706 | July 19th | 
The relatively high records for Diatoms in 1912 and 1913 are due in the 
former case to the usual June maximum of Rhizosolenta and Guinardia, and 
in the latter case to a quite exceptional invasion of Asterionella japonica— 
the only occasion in our records when this genus has been abundant in the 
Irish Sea. We regard it as quite a rare form here. It is exceedingly 
abundant to the south of Iceland (Ove Paulsen) and also in the Gulf of Lyons 
(Pavillard). 
COPEPODA. 
The following table shows the total numbers recorded of our six important 
species of Copepoda in the years 1909 and 1910 :— 
1910. 1909. 
Oithona helgolandica — ... 872,678 465,066 
Pseudocalanus elongatus 308,926 309,973 
Acartia clausi os 340,631 63,373 
Paracalanus parvus — ... 217,633 54,120 
Temora longicornis P 147,043 62,059 
Calanus finmarchicus ... 15,418 21,412 
* An exceptionally large haul at such an early date—due apparently to several moderately 
large swarms of different Copepoda occurring together, viz., Calanus, Pseudocalanus, Temora, 
and Acartia, 
