270 
not a single specimen of the forma sqnamosa occurs. It must 
remain open to future investigations, which factors determine the 
development into the forma squamosa , or into the forma typica. 
Another feature of great biological interest is the faet that the 
pupas of the species settie down in crowded assemblies, evidently 
not determined by the characters of the substratum. In Janthina 
f. inst. no special part of the shell is preferred; but where the 
pupas fix themselves, they do so in great numbers, and closely 
crowded. The youngest stages therefore are curiously homogeneous, 
as to the development of the individuals. 
Very soon the aspect of a group changes. Some of the animals 
develop at a great speed, whereas others seem to be checked in 
their development at one stage or other, or even to be outnumb- 
ered, and the larger the best developed specimens of a group be- 
come, the fewer animals the group contains. This may of course be 
due to cannibalism, although this factor, especially in younger spec¬ 
imens, hardly can be of any consequence, and I am inelined to 
believe that other circumstances play a prominent part in the fate 
of the individuals. This question cannot of course be definitly sett- 
led by preserved specimens. 
Genus Poecilasma Darwin. 
Poecilasma Kaempfevi Darwin. 
37° 45’ S, 150° 10’ E., 150—260 fathoms. „Endeavour“ 14/IX 14. One 
specimen (together with Heteralepas Dannevigi). 
The specimen belongs to the subsp. litum Pilsbry. It has a 
capitulum length of 9, width 6 mm, a peduncle length of 2,5 mm. 
Genus Megalasma (Hoek) Pilsbry. 
Megalasma striatum Hoek. 
3 miles S. W. of Tueuran, 300 fathoms. 10/III 14. Several specimens 
on the spines of a Cidaris. 
21 miles W. 7* S. of Bonomisaki, 220 fathoms. „Hyaton Maru“ 13/V 14. 
One large specimen. 
The specimens in some cases differ from Hoek’s description 
(1883) in having an externally visible, short peduncle (Fig. 29). 
