: 
: 
| Mr Potts, The gall-forming Crab, Hapalocarcinus. 463 
seriously upon the space in chamber B and partially fill up 
chamber A. The formation of the gall does not permanently 
suppress the further development of the branch of which it forms 
part. A perfect forest of twigs cover the surface of closed galls of 
some standing and occasionally examples are found in which the 
gall is the foundation of a complex branching system. In these 
cases, the galls can evidently lay claim to a respectable antiquity. 
_ The youngest females, which are found in galls in which 
ehamber A alone is formed, have a carapace length of 1:5 mm. 
and their sex is hardly recognisable. They have a narrow ab- 
domen with no trace of swimmerets, there are no reproductive 
apertures and the genital gland has not developed. But there is 
equally no sign of male characters and a perfect gradation exists 
from these apparently sexless forms up to the adult females. In 
the next stage, though the abdomen is very little broader, rudi- 
ments of the swimmerets appear and also the female apertures on 
the sternum opposite the third thoracic legs. The succeeding 
Intermediates show a gradual increase in the size of the abdomen 
which becomes accelerated when the great growth of the ovary 
begins. 
__ For some time I was unable to find the male of the species 
‘though I examined as many as a hundred galls. But at length 
on opening one I found it occupied by a female with her recently 
moulted skin and a much smaller individual of about 1 mm. cara- 
pace length. This was identified as a male on account of the well 
developed and typical copulatory styles and a pair of enormous 
testes full of mature spermatozoa which showed up as opaque 
white structures in the cephalothorax. From this discovery 
Iconclude that the male is normally very much smaller than the 
adult female and not even so large as the young immature females 
which are found in the least developed galls. Also that he is free- 
living and visits the females within the galls, copulation taking 
Place at a period when the gall is still open and the ovary is 
beginning to grow. As in the other Brachyura so here it only 
occurs just after the female has moulted. Soon after a stock of 
‘Sperm has thus been secured the gall closes up so far that the 
visits of other males are barred. But the female begins to lay 
eggs and lays apparently brood after brood which develop within. 
the ample shelter of the abdomen until they reach the Zoaea 
‘stage. Then the larvae are liberated to the exterior through the 
tiny circular outlets of the gall. 
____ This curious life history presents points of resemblance to and 
difference from that of the related genus, Cryptochirus* so far as 
* J. R. Henderson, Ann. Mag. Nat. Hist., Ser. 7, vol. xvi. pp. 211—219. 
These remarks only apply to C. dimorphus. Such observations as I have been able 
to make upon C. coralliodytes Heller will be given in the full paper. a 
