Hapalocarcinus, the Gall-forming Crab, etc. 59 
The male is figured in the ventral and dorsaal spects where, though 
it is so small, it will be seen that none of its organs show any signs of 
degeneracy. This is so for the internal as well as the external organs. 
The alimentary canal is apparently quite normal; the buccal append- 
ages resemble almost exactly those of the female. Yet it will be seen 
that the reproductive organs reach a remarkable state of development. 
The opaque white structures which I have referred to above occupy 
a large part of the dorsal surface of the cephalothorax. The fact that 
they are full of mature spermatozoa leads one to regard them as 
vesicule seminales rather than testes and it is difficult to recognise in 
them the tubular shape of the testes and vasa deferentia of the Deca- 
poda generally. A noticeable point is that the spermatozoa all lie 
free in vesicula seminalis and are not contained in spermatophores. 
The absence of tubular testes at the time of examination is probably 
due to the fact that the male is short-lived and spermatogenesis is 
confined to a short period, during which all the germ cells are rapidly 
used up and enormous numbers of spermatozoa are produced. 
Fig. 13.—Copulatory appendages of male of Hapalocarcinus. X50. app. 1, first abdominal 
appendage; app. 2, second abdominal appendage. 
Fie. 14.—Third maxilliped of male Hapalocarcinus. X80, to show the small number of sete 
fringing the inner border. 
The spermatozoa are very tiny discs about 5 uw in diameter. They are 
without marginal processes. 
In the female, spermatozoa are found in the spermathece, which 
are rather large, rounded sacs in the ventral part of the body cavity, 
just at the female openings. They are exactly like those seen in the 
vesiculz seminales, but are cemented together evidently by a substance 
secreted by the spermathecal epithelium. 
As is usual in the Brachyura, the appendages on each side of the first 
two abdominal segments unite to form a single copulatory organ. 
The anterior appendage is tubular; its cavity is large at the base, but 
soon diminishes greatly and only widens again at the tip where it opens. 
