of the Fishery Board for Scotland. 163 
In the first young stage (Figs. 164 and 169) the two tubercles are 
present. The sternum is covered with the minute “needle-point” 
cilia, except over the surfaces covered by the abdomen. 
Sexual characters are not seen. They were made out in crabs 
measuring 5} and 53 mm. across. 
Sizes OF THE DIFFERENT STAGES. 
The drawings of all the stages are done on the same scale. 
Alongside the enlarged drawings of the I.-IV. Zoée and of the 
Megalops, first and second young stages, outlines are placed representa- 
tive of the natural size. 
In comparing the Zoéa stages, the distance between the tips of the 
rostral and dorsal spines was taken as the standard of measure- 
ment, 
Distance between 
the Tips of Rostral 
= Number of I we 
Stage. dueairn ead and Dorsal Spines. 
Min ° 
I 2 cS als 
Il. 1 2. 
iti #7 2 2:3: 2-4, 
IV. 1 3. 
Megalops and succeeding Stages. 
For the Megalops and succeeding stages two measurements were taken 
of the carapace—(1) The greatest breadth. In all, except the Megalops, 
this is at a fixed point, viz. behind the hindmost lateral teeth. (2) 
Length of the carapace, 7.e. the distance between the tip of the rostrum 
and middle of the hind border of the carapace. 
Greatest Greatest 
Stage. N umber of Breadth. Length. 
Specimens. 
| Mn. Mm. 
| cme eos theta 
| Megalops. | 1 | aleilis Tes 
| 
ene ce 2 | 1:6: 1:75 V7 21-7 
2 1 2°4 2:2 
3 1 3°4 acl 
38a 1 31 
pe 1 3°9 3'3 
| 4a 1 | 4:0 
