10 G. O. Sars. 
the exposed part of the body. The edges of the carapace, 
and the several spines occurring on the body were of a fine 
chestnut colour. The eyes were dark brown. Within the 
exposed part of the body, the capacious intestinal tube was 
plainly seen, owing to its dark contents. 
Remarks—From the European species, A. cancri- 
formis, Schiffer, of which I have had specimens for exa- 
mination, the Australian form is chiefly distinguished by 
the greater number of caudal (non-limb-bearing) segments. 
In A. cancriformis I have never found more than 6 such 
segments, whereas their number in the Australian species is 
twice as large. It is also for this reason that the exposed 
part of the body in the latter species appears longer in 
proportion to the carapace. Otherwise the 2 species seem 
to be very closely allied. 
Biological Observations. 
I first observed the above-mentioned specimens on the 
27th May in one of the smaller of my aquaria, prepared on 
the 17th of the same month. It was at that time still in the 
larval condition, though rather advanced, and of a reddish 
brown colour. It moved about along the bottom of the 
aquarium chiefly by the aid of the 2nd pair of antenne, 
which, as in the larve of other Apodide, at this period con- 
stitute powerful biramose oars. In the course of the suc- 
ceeding days it grew very rapidly, and before the close of 
the month it had attained almost double the size, the larval 
stages having been long before passed through. During the 
next month it was watched every day, and 1 had great 
pleasure in witnessing the rapid growth and the peculiar 
habits of the animal. It seemed to thrive exceedingly well 
and was very voracious, feeding eagerly upon the small 
