80 H. J. HANSEN. 
vaulted than in Leptosphzroma, in the two specimens 
mentioned with about ten or twelve large half-developed 
young. Inthe females of these two genera it is, however, 
impossible to detect even the slightest vestige of 
marsupial lamelle. In Cassidinidea a transverse 
lobe is observed occupying nearly the area between third and 
fourth pairs of thoracic legs; its free anterior margin is 
situated about in the transverse line between the two legs of 
third pair, while laterally it is curved backwards, originating 
at the insertion of fourth pair; in Leptospheroma this 
lobe is somewhat shorter. This lobe is the front end of the 
lower wall of an external pouch occupying, as in Ancinella, 
somewhat more than the posterior half of the lower surface 
of thorax, but the wall is much thicker than in the last-named 
genus, in accordance with the fact that it is not overlapped 
by marsupial lamelle. The anterior part of the incubatory 
chamber seems to be a rather similar pouch, which is smaller, 
closed in front, and without any free lobe behind. But now 
we come to a serious difficulty. I lifted the free lobe men- 
tioned, which at its base seems to be rather firmly connected 
with the posterior margin of the lower wall of the front part 
of the incubatory chamber; I could not with any certainty 
discover apertures in the junction between the two walls, but 
pulling more vigorously on the free lobe, the junction named 
was broken, and a broad entrance to the incubatory chamber 
was formed. The posterior half of this chamber is a pouch 
formed as in Cymodocella and Ancinella, but what may 
the anterior half be? Is it formed by a folding of the skin 
from in front backwards—as the posterior half is formed by 
folding in the opposite direction—or by the fusion of the 
marsupial lamelle with each other and with the lower surface 
of thorax along the insertions of the legs? I think the first 
alternative to be the right interpretation, but I cannot under- 
stand the fact that the posterior margin of its wall seems to 
be connected with the upper surface of the lower wall of the 
posterior pouch at the base of the free lobe. The animals 
examined are very small, and my material quite insufficient 
