326 Records of the Indian Museum. PVior.- Mie 
As in the other cases we have two growth-factors for stage 4. 
Some individuals by a factor 1°57 attain sexual maturity direct 
and reach stage 2, the remainder have a growth factor 1°29 (the 
same as for the female) and thus reach stage 3, whence by a 
factor of 1°57 they should attain stage 1. Unfortunately no ex- 
amples were obtained of this stage, but calculation shows that it 
should have a length of 3:69 mm_, while the final stage of the 
female should be 4:2 mm. in length. 
During the last few weeks a further series of tow-nettings has 
been received. ‘These were taken in the region at the mouth of 
Tavoy River (vide infra plate xiv), and their chief interest and 
importance lies in the fact that they contain large numbers of 
Paracalanus aculeatus, Giesbrecht, among which are numerous 
examples of the hitherto unknown male, a detailed description of 
which will, I hope, be published shortly. 
A series of measurements of individuals of both sexes has 
been carried out and the results are given in text-figure V. 
In the case of the female only two stages have at present 
been obtained, and these apparently correspond to the last imma-~ 
ture stage (stage 3), and the first sexually mature form (stage 
2); the members of this latter group correspond exactly with 
the description of P. aculeatus both as regards size and structure. 
As is shown in the accompanying table, the growth-factor 
between these two stages is 1°284. 
Paracalanus aculeatus +. | Observed size. Growth factor. 
mm. | 
Stage 3 (?) “* oe ele 0°874 | : 
” 2 (?) oe ae 5 103 EAXO) } 1°284. 
The males fall into a series of four stages corresponding to 
stages 4 to I. The individuals of stage 3 correspond exactly 
with the description given by Cleve (Igor), so far as their structure 
is concerned, but are on the whole slightly smaller, measuring only 
0°873 mm. as opposed to 1'1 mm. in his specimens. 
Stage 2 corresponds exactly with the adult females, while 
stage 1 is slightly different, having a series of spines on the margin 
of the second joint of the exopod in the 2nd-4th pairs of legs. 
The average measurenients of these four stages are given 
below in the accompanying table. 
| Growth- 
Paracalanus aculeatus ~. | Observed size. | Calculated size. 
| factor. 
| ea ae - a | 
mm. mim, 
Stage 4 aie arom 0°667 0°667 1°45 ot 1°284 
anne 5} 0 2 | 0'873 0°856 | 1°45 
eee 56 | 0°996 0'967 | set 
5 see 1°238 1°24! 
