314 Records of the Indian Museum. [VoL V ie 
(7) Cleve: Record of a voyage made by Thorild Wulff 
to and from Bombay. Arkiv for Zoologi, Band 
i, 1903-04. Stockholm. 
During the early months of I9g1II and again in November of 
the same year the R.IM.S. “‘Investigator’’ was carrying 
out a survey of the coast of Burma, and advantage was taken 
of the opportunity thus offered to make a collection of the 
free-living Copepoda that frequent the surface waters of this 
region. 
There was also in the Indian Museum a large collection 
made some years previously by the “‘ Investigator’ in the region 
of the coast off Chittagong; these collections have been worked 
out and the results are embodied in the following paper. 
For purposes of convenience I have divided the collections 
into two series, the first comprises those from the Chittagong 
region and the Rangoon River estuary, while the second deals 
with the collections made further south in the neighbourhood 
of the Moscos Islands and the mouth of Tavoy River. 
I.—THE GYMNOPLEA OF THE CHITTAGONG AND RANGOON RIVER 
ESTUARIES; WITH NOTES ON THE APPLICATION OF ‘‘ BROOKS’ 
LAw’’ TO THE COPEPODA AND EVIDENCE OF DIMORPHISM IN 
THIS GROUP OF CRUSTACEA. 
As regards the collection from the Chittagong region there 
is unfortunately no indication of how the collection was made, 
and whether or not it is composed of the results from several 
surface trawls or only a single one, nor is there anything to 
indicate at what time of the year it was taken; it is probable 
however that the collection was made in 1903 during the months 
of January to March as that was, I believe, the last occasion 
on which the R.I.M.S. ‘‘ Investigator ’’ was surveying in that 
locality. 
The collection from the Rangoon River estuary was made 
on three consecutive nights by means of a surface tow-net allowed 
to drift with the tide. The resulting catch was extremely copious, 
though subsequent examination showed that the actual number 
of species represented was small; but this lack of variety was 
amply compensated by the fact that out of a total of seven (or 
possibly eight) species five were new to science and as regards the 
Labidocera euchaeta, Giesbrecht, not only was the corresponding 
male, hitherto unknown present in large numbers, but a probably 
dimorphic form was also obtained. The main bulk of the collec- 
tion consisted of large numbers of Acvocalanus inermis, sp nov. and 
Labidocera euchaeta, Giesbrecht, in various stages of development, 
and a study of these forms and the various changes that take 
place during the growth of these two species has led to results 
of very considerable interest. So many external factors such as 
temperature, salinity, or food supply, may possibly produce varta- 
