Dr. R. Kossman on the Entoniscide. 85 
surface to the underside of the head, which it passes to a 
greater or less extent.” Giard (5, p. 685) in a similar 
manner, with respect to H. Cavolinii and LE. Moniezi/, speaks 
of ‘chambres incubatrices” of peculiar arrangement, very 
different from that occurring in EH. cancrorum. Lastly, 
Fraisse also shares in this view. He speaks of (4, p. 11) 
“the much-folded thin membrane, which, likewise originating 
from two edges of the great chitinous stem, forms the true 
closed brood-chamber.” And further on (p. 12), when he 
speaks of the lateral brood-chambers, which, like Giard, he 
ascribes to H. Cavolinii, he represents them as leaf-like in 
the young state, and says, “ In transverse sections it appears 
that the interior is occupied by a loose connective tissue, the 
interspaces of which are frequently filled with coagulum. 
In fully developed specimens a lumen has been formed, which 
is occupied only by ova or larvee.” . 
Whoever compares with these statements and the figures 
accompanying them my figure (Pl. [X. fig. 1), drawn from 
life, will at once perceive upon what the errors of these three 
naturalists are founded. Fritz Miiller, evidently accustomed, 
from the example of H. porcellane, to find the parasite im- 
bedded in a very delicate tissue, could not make up his mind 
to regard the tougher sac in which E. cancrorum lay also as 
a constituent of the host, and to remove it in preparation ; 
and when he had once taken the grave step of interpreting 
this sac, when it coats the brood-chamber, as the wall of the 
latter belonging to the parasite itself, it was easy for Giard 
and Fraisse to follow him in so doing. Fraisse indeed cut 
open the sac in front, and found in it the anterior pair of 
brood-leaves, which he describes clearly enough (p. 11) ; but 
as the wall of the sac in which the parasite lay was adherent 
to the outer surface (which happens when the living animal 
is injured, by the secretion of a quickly coagulating fluid, pro- 
bably the cement serving for the attachment of the ova when 
laid), Fraisse seems to have separated, together with the wall 
of the sac, the more delicate parts of the brood-leaves from 
the ramified chitinous ribs which traverse the latter like the 
veins of a leaf. What was thus set free might well be com- 
pared, as it is by him, to a biserial plume; and it appears 
explicable that he should regard these plume-like artificial 
products not as brood-leaves, but as “metamorphosed limbs.” 
His error regarding the posterior brood-leaves seems to have 
been produced somewhat differently. In young specimens he 
appears to have prepared them freely, without knowing that 
he had done so, and consequently he describes them quite cor- 
rectly. In older specimens, however, he did not prepare them 
