1912.] R. B. SEYMOUR-SEWELL: Surface-Living Copepoda. 349 
II.—THE GYMNOPLEA OF THE S. BURMA COAST AND 
Moscos ISLAND. 
The regions of the coast of Burma in which the collections 
were made comprise (1) Hinzé Basin (lat. 14° 41’ 95” N., long. 
97° 53’ 00” E.) and its neighbouring waters, and (2) the region 
extending from the Middle Moscos South Island (lat. 14° 15’ 95” 
N.) on the north to the entrance of Tavoy River (lat. 13° 31’ 45” 
N.) on the south, and from the coast line on the east to about 
latitude 97° 40’ 00” on the west. Over the whole area the plankton 
was found to be abundant, especially during the later part of the 
season, 7.¢. March and early April, and the following diatoms were 
identified :— 
Amphulonche belonotdes. 
Astertonella glactalts. 
A stertonella challengerensts. 
Asteromphalus hookert. 
Bactertastrum delicatulum, 
Bacteriastrum spirillum. 
Bactertastvrum varians. 
Eucampta zoodiacus, 
Guinardia flaccida. 
Hemiaulus hauckit. 
Melosirva borrert. 
Nitzschia closterium. 
Nitzschia lineola. 
Nitzschia migrans. 
Chaetoceras criophilum. 
Chaetoceras coarctatum. 
Chaetoceras compressum. 
Chaetoceras densum. 
Chaetoceras dichaeta. 
Chaetoceras didymum. 
Chaetoceras diversum. 
Chaetoceras furca. 
Chaetoceras lorenzianum. 
Climacodium biconcavum. 
Climacodium frauenfeldianum. 
Coscinodiscus centralis. 
Coscinodiscus excentricus. 
Planktoniella sol. 
Pyrocystis lunula. 
Rhizosolenia alata. 
Rhizosolema avafurensis, 
Rhizosolenia calcar avis. 
Rhizosolenta robusta. 
Rhizosolenia setigera. 
Rhizosolenta shrubsolet. 
Rhizosolenia stolterfothit. 
Rhizosolema styltformts. 
Skeletonema costatum. 
Thalassiosiva antarctica. 
Thalasstostra aurivillit. 
Coscinodiscus lineatus. Thalasstosira longissima. 
It was soon seen, however, that although in the main the 
same diatoms were present in all the different parts of this region, 
in certain very definite areas the proportional distribution was 
extremely different, and this appeared to be constant during the 
whole of the two months in which the investigations were carried 
out. So striking were the differences that one could tell at a glance 
from which particular area the collection of plankton had been 
made, I was thus able to divide the region, from the Middle 
Moscos: Islands to Tavoy River, into four areas, each differing 
from the other in their surface plankton, and in the accompany- 
ing map (pl. xiv) I have indicated, as nearly as possible, the 
limits of these areas. 
Area I extends from the mainland to some distance west of 
the Middle Moscos Islands, and from there is continued south- 
ward along the coast in a narrow band, .. The diatom flora of 
