125 
the circumference of the much greater circle which would be neces- 
sary were the same amount of ambulacral surface supplied by ten 
arms only. Moreover, in case of injury, the loss of an arm to a 
multibrachiate species is of much less economic importance than 
to a ten armed species. It is probably due to these causes that 
almost all of the shallow water comatulids are multibrachiate, except 
those so small as to render unneccessary any further reduction 
in size. 
It is quite possible that a more or less general redistribution 
of ten armed young, and the adults of ten armed species, may 
take place during the period of the monsoon; for Chadwick mentions 
that, in the case of Antedon bifida, fishermen state that they are 
found more abundantly on their creels after stormy weather, which 
I take to mean that the motion of the water during storms 
stimulates them to activity, and causes them to swim about. Jf 
the same were true in the tropics, this would doubtless be an 
important factor in the distribution of the group!) 
The distribution of the recent crinoids differs in many parti- 
culars from that of the other echinoderm groups, and offers many 
points of especial interest, some of which, as I first noticed them 
when studying this collection, may appropriately be considered here. 
In the case of the littoral crinoids the chief factors in the 
distribution are the permanent currents, and the temporary currents 
Or washing action induced by winds blowing on shore at less than 
a right angle. No coastline is free from these influences. The 
Foung from a littoral parent, therefore, would form a linear, nar- 
rowly fan-shaped, or broadly fan-shaped dispersal figure, according 
to the strength of the current at the breeding season. These 
Joung again would scatter their young in similar figures, and thus 
7) While on board the United States Fisheries steamer , Albatross" in 
the Philippine Islands, Dr. Paul Bartsch captured some small ten 
armed comatulids which were attracted to the surface by an electric 
light lowered over the ship's side at night. This would suggest that 
the young were very sensitive to stimuli. 
